Returns the main thread.
static VALUE rb_thread_s_main(VALUE klass) { return rb_thread_main(); }
Threads are the Ruby implementation for a concurrent programming model.
Programs that require multiple threads of execution are a perfect candidate for Ruby's Thread
class.
For example, we can create a new thread separate from the main thread's execution using ::new
.
thr = Thread.new { puts "Whats the big deal" }
Then we are able to pause the execution of the main thread and allow our new thread to finish, using join
:
thr.join #=> "Whats the big deal"
If we don't call thr.join
before the main thread terminates, then all other threads including thr
will be killed.
Alternatively, you can use an array for handling multiple threads at once, like in the following example:
threads = [] threads << Thread.new { puts "Whats the big deal" } threads << Thread.new { 3.times { puts "Threads are fun!" } }
After creating a few threads we wait for them all to finish consecutively.
threads.each { |thr| thr.join }
Thread
initialization¶ ↑In order to create new threads, Ruby provides ::new
, ::start
, and ::fork
. A block must be provided with each of these methods, otherwise a ThreadError
will be raised.
When subclassing the Thread
class, the initialize
method of your subclass will be ignored by ::start
and ::fork
. Otherwise, be sure to call super in your initialize
method.
Thread
termination¶ ↑For terminating threads, Ruby provides a variety of ways to do this.
The class method ::kill
, is meant to exit a given thread:
thr = Thread.new { ... } Thread.kill(thr) # sends exit() to thr
Alternatively, you can use the instance method exit
, or any of its aliases kill
or terminate
.
thr.exit
Thread
status¶ ↑Ruby provides a few instance methods for querying the state of a given thread. To get a string with the current thread's state use status
thr = Thread.new { sleep } thr.status # => "sleep" thr.exit thr.status # => false
You can also use alive?
to tell if the thread is running or sleeping, and stop?
if the thread is dead or sleeping.
Thread
variables and scope¶ ↑Since threads are created with blocks, the same rules apply to other Ruby blocks for variable scope. Any local variables created within this block are accessible to only this thread.
Each fiber has its own bucket for Thread#[]
storage. When you set a new fiber-local it is only accessible within this Fiber
. To illustrate:
Thread.new { Thread.current[:foo] = "bar" Fiber.new { p Thread.current[:foo] # => nil }.resume }.join
This example uses []
for getting and []=
for setting fiber-locals, you can also use keys
to list the fiber-locals for a given thread and key?
to check if a fiber-local exists.
When it comes to thread-locals, they are accessible within the entire scope of the thread. Given the following example:
Thread.new{ Thread.current.thread_variable_set(:foo, 1) p Thread.current.thread_variable_get(:foo) # => 1 Fiber.new{ Thread.current.thread_variable_set(:foo, 2) p Thread.current.thread_variable_get(:foo) # => 2 }.resume p Thread.current.thread_variable_get(:foo) # => 2 }.join
You can see that the thread-local :foo
carried over into the fiber and was changed to 2
by the end of the thread.
This example makes use of thread_variable_set
to create new thread-locals, and thread_variable_get
to reference them.
There is also thread_variables
to list all thread-locals, and thread_variable?
to check if a given thread-local exists.
Exception
handling¶ ↑Any thread can raise an exception using the raise
instance method, which operates similarly to Kernel#raise
.
However, it's important to note that an exception that occurs in any thread except the main thread depends on abort_on_exception
. This option is false
by default, meaning that any unhandled exception will cause the thread to terminate silently when waited on by either join
or value
. You can change this default by either abort_on_exception=
true
or setting $DEBUG to true
.
With the addition of the class method ::handle_interrupt
, you can now handle exceptions asynchronously with threads.
Ruby provides a few ways to support scheduling threads in your program.
The first way is by using the class method ::stop
, to put the current running thread to sleep and schedule the execution of another thread.
Once a thread is asleep, you can use the instance method wakeup
to mark your thread as eligible for scheduling.
You can also try ::pass
, which attempts to pass execution to another thread but is dependent on the OS whether a running thread will switch or not. The same goes for priority
, which lets you hint to the thread scheduler which threads you want to take precedence when passing execution. This method is also dependent on the OS and may be ignored on some platforms.
Returns the thread debug level. Available only if compiled with THREAD_DEBUG=-1.
static VALUE rb_thread_s_debug(void) { return INT2NUM(rb_thread_debug_enabled); }
Sets the thread debug level. Available only if compiled with THREAD_DEBUG=-1.
static VALUE rb_thread_s_debug_set(VALUE self, VALUE val) { rb_thread_debug_enabled = RTEST(val) ? NUM2INT(val) : 0; return val; }
Returns the status of the global “abort on exception'' condition.
The default is false
.
When set to true
, if any thread is aborted by an exception, the raised exception will be re-raised in the main thread.
Can also be specified by the global $DEBUG flag or command line option -d
.
See also ::abort_on_exception=
.
There is also an instance level method to set this for a specific thread, see abort_on_exception
.
static VALUE rb_thread_s_abort_exc(void) { return GET_THREAD()->vm->thread_abort_on_exception ? Qtrue : Qfalse; }
When set to true
, if any thread is aborted by an exception, the raised exception will be re-raised in the main thread. Returns the new state.
Thread.abort_on_exception = true t1 = Thread.new do puts "In new thread" raise "Exception from thread" end sleep(1) puts "not reached"
This will produce:
In new thread prog.rb:4: Exception from thread (RuntimeError) from prog.rb:2:in `initialize' from prog.rb:2:in `new' from prog.rb:2
See also ::abort_on_exception
.
There is also an instance level method to set this for a specific thread, see abort_on_exception=
.
static VALUE rb_thread_s_abort_exc_set(VALUE self, VALUE val) { GET_THREAD()->vm->thread_abort_on_exception = RTEST(val); return val; }
Returns the currently executing thread.
Thread.current #=> #<Thread:0x401bdf4c run>
static VALUE thread_s_current(VALUE klass) { return rb_thread_current(); }
Wraps the block in a single, VM-global Mutex.synchronize
, returning the value of the block. A thread executing inside the exclusive section will only block other threads which also use the Thread.exclusive
mechanism.
# File prelude.rb, line 11 def self.exclusive(&block) warn "Thread.exclusive is deprecated, use Thread::Mutex", caller MUTEX_FOR_THREAD_EXCLUSIVE.synchronize(&block) end
Terminates the currently running thread and schedules another thread to be run.
If this thread is already marked to be killed, ::exit
returns the Thread
.
If this is the main thread, or the last thread, exit the process.
static VALUE rb_thread_exit(void) { rb_thread_t *th = GET_THREAD(); return rb_thread_kill(th->self); }
Changes asynchronous interrupt timing.
interrupt means asynchronous event and corresponding procedure by Thread#raise
, Thread#kill
, signal trap (not supported yet) and main thread termination (if main thread terminates, then all other thread will be killed).
The given hash
has pairs like ExceptionClass => :TimingSymbol
. Where the ExceptionClass is the interrupt handled by the given block. The TimingSymbol can be one of the following symbols:
:immediate
Invoke interrupts immediately.
:on_blocking
Invoke interrupts while BlockingOperation.
:never
Never invoke all interrupts.
BlockingOperation means that the operation will block the calling thread, such as read and write. On CRuby implementation, BlockingOperation is any operation executed without GVL.
Masked asynchronous interrupts are delayed until they are enabled. This method is similar to sigprocmask(3).
Asynchronous interrupts are difficult to use.
If you need to communicate between threads, please consider to use another way such as Queue
.
Or use them with deep understanding about this method.
In this example, we can guard from Thread#raise
exceptions.
Using the :never
TimingSymbol the RuntimeError
exception will always be ignored in the first block of the main thread. In the second ::handle_interrupt
block we can purposefully handle RuntimeError
exceptions.
th = Thread.new do Thread.handle_interrupt(RuntimeError => :never) { begin # You can write resource allocation code safely. Thread.handle_interrupt(RuntimeError => :immediate) { # ... } ensure # You can write resource deallocation code safely. end } end Thread.pass # ... th.raise "stop"
While we are ignoring the RuntimeError
exception, it's safe to write our resource allocation code. Then, the ensure block is where we can safely deallocate your resources.
In the next example, we will guard from the Timeout::Error exception. This will help prevent from leaking resources when Timeout::Error exceptions occur during normal ensure clause. For this example we use the help of the standard library Timeout, from lib/timeout.rb
require 'timeout' Thread.handle_interrupt(Timeout::Error => :never) { timeout(10){ # Timeout::Error doesn't occur here Thread.handle_interrupt(Timeout::Error => :on_blocking) { # possible to be killed by Timeout::Error # while blocking operation } # Timeout::Error doesn't occur here } }
In the first part of the timeout
block, we can rely on Timeout::Error being ignored. Then in the Timeout::Error => :on_blocking
block, any operation that will block the calling thread is susceptible to a Timeout::Error exception being raised.
It's possible to stack multiple levels of ::handle_interrupt
blocks in order to control more than one ExceptionClass and TimingSymbol at a time.
Thread.handle_interrupt(FooError => :never) { Thread.handle_interrupt(BarError => :never) { # FooError and BarError are prohibited. } }
All exceptions inherited from the ExceptionClass parameter will be considered.
Thread.handle_interrupt(Exception => :never) { # all exceptions inherited from Exception are prohibited. }
static VALUE rb_thread_s_handle_interrupt(VALUE self, VALUE mask_arg) { VALUE mask; rb_execution_context_t * volatile ec = GET_EC(); rb_thread_t * volatile th = rb_ec_thread_ptr(ec); volatile VALUE r = Qnil; enum ruby_tag_type state; if (!rb_block_given_p()) { rb_raise(rb_eArgError, "block is needed."); } mask = 0; mask_arg = rb_to_hash_type(mask_arg); rb_hash_foreach(mask_arg, handle_interrupt_arg_check_i, (VALUE)&mask); if (!mask) { return rb_yield(Qnil); } OBJ_FREEZE_RAW(mask); rb_ary_push(th->pending_interrupt_mask_stack, mask); if (!rb_threadptr_pending_interrupt_empty_p(th)) { th->pending_interrupt_queue_checked = 0; RUBY_VM_SET_INTERRUPT(th->ec); } EC_PUSH_TAG(th->ec); if ((state = EC_EXEC_TAG()) == TAG_NONE) { r = rb_yield(Qnil); } EC_POP_TAG(); rb_ary_pop(th->pending_interrupt_mask_stack); if (!rb_threadptr_pending_interrupt_empty_p(th)) { th->pending_interrupt_queue_checked = 0; RUBY_VM_SET_INTERRUPT(th->ec); } RUBY_VM_CHECK_INTS(th->ec); if (state) { EC_JUMP_TAG(th->ec, state); } return r; }
Causes the given thread
to exit, see also Thread::exit
.
count = 0 a = Thread.new { loop { count += 1 } } sleep(0.1) #=> 0 Thread.kill(a) #=> #<Thread:0x401b3d30 dead> count #=> 93947 a.alive? #=> false
static VALUE rb_thread_s_kill(VALUE obj, VALUE th) { return rb_thread_kill(th); }
Returns an array of Thread
objects for all threads that are either runnable or stopped.
Thread.new { sleep(200) } Thread.new { 1000000.times {|i| i*i } } Thread.new { Thread.stop } Thread.list.each {|t| p t}
This will produce:
#<Thread:0x401b3e84 sleep> #<Thread:0x401b3f38 run> #<Thread:0x401b3fb0 sleep> #<Thread:0x401bdf4c run>
VALUE rb_thread_list(void) { VALUE ary = rb_ary_new(); rb_vm_t *vm = GET_THREAD()->vm; rb_thread_t *th = 0; list_for_each(&vm->living_threads, th, vmlt_node) { switch (th->status) { case THREAD_RUNNABLE: case THREAD_STOPPED: case THREAD_STOPPED_FOREVER: rb_ary_push(ary, th->self); default: break; } } return ary; }
Returns the main thread.
static VALUE rb_thread_s_main(VALUE klass) { return rb_thread_main(); }
Creates a new thread executing the given block.
Any args
given to ::new
will be passed to the block:
arr = [] a, b, c = 1, 2, 3 Thread.new(a,b,c) { |d,e,f| arr << d << e << f }.join arr #=> [1, 2, 3]
A ThreadError
exception is raised if ::new
is called without a block.
If you're going to subclass Thread
, be sure to call super in your initialize
method, otherwise a ThreadError
will be raised.
static VALUE thread_s_new(int argc, VALUE *argv, VALUE klass) { rb_thread_t *th; VALUE thread = rb_thread_alloc(klass); if (GET_VM()->main_thread->status == THREAD_KILLED) rb_raise(rb_eThreadError, "can't alloc thread"); rb_obj_call_init(thread, argc, argv); th = rb_thread_ptr(thread); if (!threadptr_initialized(th)) { rb_raise(rb_eThreadError, "uninitialized thread - check `%"PRIsVALUE"#initialize'", klass); } return thread; }
Give the thread scheduler a hint to pass execution to another thread. A running thread may or may not switch, it depends on OS and processor.
static VALUE thread_s_pass(VALUE klass) { rb_thread_schedule(); return Qnil; }
Returns whether or not the asynchronous queue is empty.
Since Thread::handle_interrupt
can be used to defer asynchronous events, this method can be used to determine if there are any deferred events.
If you find this method returns true, then you may finish :never
blocks.
For example, the following method processes deferred asynchronous events immediately.
def Thread.kick_interrupt_immediately Thread.handle_interrupt(Object => :immediate) { Thread.pass } end
If error
is given, then check only for error
type deferred events.
th = Thread.new{ Thread.handle_interrupt(RuntimeError => :on_blocking){ while true ... # reach safe point to invoke interrupt if Thread.pending_interrupt? Thread.handle_interrupt(Object => :immediate){} end ... end } } ... th.raise # stop thread
This example can also be written as the following, which you should use to avoid asynchronous interrupts.
flag = true th = Thread.new{ Thread.handle_interrupt(RuntimeError => :on_blocking){ while true ... # reach safe point to invoke interrupt break if flag == false ... end } } ... flag = false # stop thread
static VALUE rb_thread_s_pending_interrupt_p(int argc, VALUE *argv, VALUE self) { return rb_thread_pending_interrupt_p(argc, argv, GET_THREAD()->self); }
Returns the status of the global “report on exception'' condition.
The default is true
since Ruby 2.5.
All threads created when this flag is true will report a message on $stderr if an exception kills the thread.
Thread.new { 1.times { raise } }
will produce this output on $stderr:
#<Thread:...> terminated with exception (report_on_exception is true): Traceback (most recent call last): 2: from -e:1:in `block in <main>' 1: from -e:1:in `times'
This is done to catch errors in threads early. In some cases, you might not want this output. There are multiple ways to avoid the extra output:
If the exception is not intended, the best is to fix the cause of the exception so it does not happen anymore.
If the exception is intended, it might be better to rescue it closer to where it is raised rather then let it kill the Thread
.
If it is guaranteed the Thread
will be joined with Thread#join
or Thread#value
, then it is safe to disable this report with Thread.current.report_on_exception = false
when starting the Thread
. However, this might handle the exception much later, or not at all if the Thread
is never joined due to the parent thread being blocked, etc.
See also ::report_on_exception=
.
There is also an instance level method to set this for a specific thread, see report_on_exception=
.
static VALUE rb_thread_s_report_exc(void) { return GET_THREAD()->vm->thread_report_on_exception ? Qtrue : Qfalse; }
Returns the new state. When set to true
, all threads created afterwards will inherit the condition and report a message on $stderr if an exception kills a thread:
Thread.report_on_exception = true t1 = Thread.new do puts "In new thread" raise "Exception from thread" end sleep(1) puts "In the main thread"
This will produce:
In new thread #<Thread:...prog.rb:2> terminated with exception (report_on_exception is true): Traceback (most recent call last): prog.rb:4:in `block in <main>': Exception from thread (RuntimeError) In the main thread
See also ::report_on_exception
.
There is also an instance level method to set this for a specific thread, see report_on_exception=
.
static VALUE rb_thread_s_report_exc_set(VALUE self, VALUE val) { GET_THREAD()->vm->thread_report_on_exception = RTEST(val); return val; }
Stops execution of the current thread, putting it into a “sleep'' state, and schedules execution of another thread.
a = Thread.new { print "a"; Thread.stop; print "c" } sleep 0.1 while a.status!='sleep' print "b" a.run a.join #=> "abc"
VALUE rb_thread_stop(void) { if (rb_thread_alone()) { rb_raise(rb_eThreadError, "stopping only thread\n\tnote: use sleep to stop forever"); } rb_thread_sleep_deadly(); return Qnil; }
Attribute Reference—Returns the value of a fiber-local variable (current thread's root fiber if not explicitly inside a Fiber
), using either a symbol or a string name. If the specified variable does not exist, returns nil
.
[ Thread.new { Thread.current["name"] = "A" }, Thread.new { Thread.current[:name] = "B" }, Thread.new { Thread.current["name"] = "C" } ].each do |th| th.join puts "#{th.inspect}: #{th[:name]}" end
This will produce:
#<Thread:0x00000002a54220 dead>: A #<Thread:0x00000002a541a8 dead>: B #<Thread:0x00000002a54130 dead>: C
Thread#[]
and Thread#[]=
are not thread-local but fiber-local. This confusion did not exist in Ruby 1.8 because fibers are only available since Ruby 1.9. Ruby 1.9 chooses that the methods behaves fiber-local to save following idiom for dynamic scope.
def meth(newvalue) begin oldvalue = Thread.current[:name] Thread.current[:name] = newvalue yield ensure Thread.current[:name] = oldvalue end end
The idiom may not work as dynamic scope if the methods are thread-local and a given block switches fiber.
f = Fiber.new { meth(1) { Fiber.yield } } meth(2) { f.resume } f.resume p Thread.current[:name] #=> nil if fiber-local #=> 2 if thread-local (The value 2 is leaked to outside of meth method.)
For thread-local variables, please see thread_variable_get
and thread_variable_set
.
static VALUE rb_thread_aref(VALUE thread, VALUE key) { ID id = rb_check_id(&key); if (!id) return Qnil; return rb_thread_local_aref(thread, id); }
Attribute Assignment—Sets or creates the value of a fiber-local variable, using either a symbol or a string.
See also Thread#[]
.
For thread-local variables, please see thread_variable_set
and thread_variable_get
.
static VALUE rb_thread_aset(VALUE self, VALUE id, VALUE val) { return rb_thread_local_aset(self, rb_to_id(id), val); }
Returns the status of the thread-local “abort on exception'' condition for this thr
.
The default is false
.
See also abort_on_exception=
.
There is also a class level method to set this for all threads, see ::abort_on_exception
.
static VALUE rb_thread_abort_exc(VALUE thread) { return rb_thread_ptr(thread)->abort_on_exception ? Qtrue : Qfalse; }
When set to true
, if this thr
is aborted by an exception, the raised exception will be re-raised in the main thread.
See also abort_on_exception
.
There is also a class level method to set this for all threads, see ::abort_on_exception=
.
static VALUE rb_thread_abort_exc_set(VALUE thread, VALUE val) { rb_thread_ptr(thread)->abort_on_exception = RTEST(val); return val; }
Adds proc as a handler for tracing.
See Thread#set_trace_func
and Kernel#set_trace_func
.
static VALUE thread_add_trace_func_m(VALUE obj, VALUE trace) { thread_add_trace_func(GET_EC(), rb_thread_ptr(obj), trace); return trace; }
Returns true
if thr
is running or sleeping.
thr = Thread.new { } thr.join #=> #<Thread:0x401b3fb0 dead> Thread.current.alive? #=> true thr.alive? #=> false
static VALUE rb_thread_alive_p(VALUE thread) { if (rb_threadptr_dead(rb_thread_ptr(thread))) { return Qfalse; } else { return Qtrue; } }
Returns the current backtrace of the target thread.
static VALUE rb_thread_backtrace_m(int argc, VALUE *argv, VALUE thval) { return rb_vm_thread_backtrace(argc, argv, thval); }
Returns the execution stack for the target thread—an array containing backtrace location objects.
See Thread::Backtrace::Location
for more information.
This method behaves similarly to Kernel#caller_locations
except it applies to a specific thread.
static VALUE rb_thread_backtrace_locations_m(int argc, VALUE *argv, VALUE thval) { return rb_vm_thread_backtrace_locations(argc, argv, thval); }
Terminates thr
and schedules another thread to be run.
If this thread is already marked to be killed, exit
returns the Thread
.
If this is the main thread, or the last thread, exits the process.
VALUE rb_thread_kill(VALUE thread) { rb_thread_t *th = rb_thread_ptr(thread); if (th->to_kill || th->status == THREAD_KILLED) { return thread; } if (th == th->vm->main_thread) { rb_exit(EXIT_SUCCESS); } thread_debug("rb_thread_kill: %p (%"PRI_THREAD_ID")\n", (void *)th, thread_id_str(th)); if (th == GET_THREAD()) { /* kill myself immediately */ rb_threadptr_to_kill(th); } else { threadptr_check_pending_interrupt_queue(th); rb_threadptr_pending_interrupt_enque(th, eKillSignal); rb_threadptr_interrupt(th); } return thread; }
static VALUE rb_thread_fetch(int argc, VALUE *argv, VALUE self) { VALUE key, val; ID id; rb_thread_t *target_th = rb_thread_ptr(self); int block_given; rb_check_arity(argc, 1, 2); key = argv[0]; block_given = rb_block_given_p(); if (block_given && argc == 2) { rb_warn("block supersedes default value argument"); } id = rb_check_id(&key); if (id == recursive_key) { return target_th->ec->local_storage_recursive_hash; } else if (id && target_th->ec->local_storage && st_lookup(target_th->ec->local_storage, id, &val)) { return val; } else if (block_given) { return rb_yield(key); } else if (argc == 1) { rb_key_err_raise(rb_sprintf("key not found: %+"PRIsVALUE, key), self, key); } else { return argv[1]; } }
Returns the ThreadGroup
which contains the given thread, or returns nil
if thr
is not a member of any group.
Thread.main.group #=> #<ThreadGroup:0x4029d914>
VALUE rb_thread_group(VALUE thread) { VALUE group = rb_thread_ptr(thread)->thgroup; return group == 0 ? Qnil : group; }
The calling thread will suspend execution and run this thr
.
Does not return until thr
exits or until the given limit
seconds have passed.
If the time limit expires, nil
will be returned, otherwise thr
is returned.
Any threads not joined will be killed when the main program exits.
If thr
had previously raised an exception and the ::abort_on_exception
or $DEBUG flags are not set, (so the exception has not yet been processed), it will be processed at this time.
a = Thread.new { print "a"; sleep(10); print "b"; print "c" } x = Thread.new { print "x"; Thread.pass; print "y"; print "z" } x.join # Let thread x finish, thread a will be killed on exit. #=> "axyz"
The following example illustrates the limit
parameter.
y = Thread.new { 4.times { sleep 0.1; puts 'tick... ' }} puts "Waiting" until y.join(0.15)
This will produce:
tick... Waiting tick... Waiting tick... tick...
static VALUE thread_join_m(int argc, VALUE *argv, VALUE self) { double delay = DELAY_INFTY; VALUE limit; rb_scan_args(argc, argv, "01", &limit); if (!NIL_P(limit)) { delay = rb_num2dbl(limit); } return thread_join(rb_thread_ptr(self), delay); }
Returns true
if the given string (or symbol) exists as a fiber-local variable.
me = Thread.current me[:oliver] = "a" me.key?(:oliver) #=> true me.key?(:stanley) #=> false
static VALUE rb_thread_key_p(VALUE self, VALUE key) { ID id = rb_check_id(&key); st_table *local_storage = rb_thread_ptr(self)->ec->local_storage; if (!id || local_storage == NULL) { return Qfalse; } else if (st_lookup(local_storage, id, 0)) { return Qtrue; } else { return Qfalse; } }
Returns an array of the names of the fiber-local variables (as Symbols).
thr = Thread.new do Thread.current[:cat] = 'meow' Thread.current["dog"] = 'woof' end thr.join #=> #<Thread:0x401b3f10 dead> thr.keys #=> [:dog, :cat]
static VALUE rb_thread_keys(VALUE self) { st_table *local_storage = rb_thread_ptr(self)->ec->local_storage; VALUE ary = rb_ary_new(); if (local_storage) { st_foreach(local_storage, thread_keys_i, ary); } return ary; }
Terminates thr
and schedules another thread to be run.
If this thread is already marked to be killed, exit
returns the Thread
.
If this is the main thread, or the last thread, exits the process.
VALUE rb_thread_kill(VALUE thread) { rb_thread_t *th = rb_thread_ptr(thread); if (th->to_kill || th->status == THREAD_KILLED) { return thread; } if (th == th->vm->main_thread) { rb_exit(EXIT_SUCCESS); } thread_debug("rb_thread_kill: %p (%"PRI_THREAD_ID")\n", (void *)th, thread_id_str(th)); if (th == GET_THREAD()) { /* kill myself immediately */ rb_threadptr_to_kill(th); } else { threadptr_check_pending_interrupt_queue(th); rb_threadptr_pending_interrupt_enque(th, eKillSignal); rb_threadptr_interrupt(th); } return thread; }
show the name of the thread.
static VALUE rb_thread_getname(VALUE thread) { return rb_thread_ptr(thread)->name; }
set given name to the ruby thread. On some platform, it may set the name to pthread and/or kernel.
static VALUE rb_thread_setname(VALUE thread, VALUE name) { rb_thread_t *target_th = rb_thread_ptr(thread); if (!NIL_P(name)) { rb_encoding *enc; StringValueCStr(name); enc = rb_enc_get(name); if (!rb_enc_asciicompat(enc)) { rb_raise(rb_eArgError, "ASCII incompatible encoding (%s)", rb_enc_name(enc)); } name = rb_str_new_frozen(name); } target_th->name = name; if (threadptr_initialized(target_th)) { native_set_another_thread_name(target_th->thread_id, name); } return name; }
Returns whether or not the asynchronous queue is empty for the target thread.
If error
is given, then check only for error
type deferred events.
See ::pending_interrupt?
for more information.
static VALUE rb_thread_pending_interrupt_p(int argc, VALUE *argv, VALUE target_thread) { rb_thread_t *target_th = rb_thread_ptr(target_thread); if (!target_th->pending_interrupt_queue) { return Qfalse; } if (rb_threadptr_pending_interrupt_empty_p(target_th)) { return Qfalse; } else { if (argc == 1) { VALUE err; rb_scan_args(argc, argv, "01", &err); if (!rb_obj_is_kind_of(err, rb_cModule)) { rb_raise(rb_eTypeError, "class or module required for rescue clause"); } if (rb_threadptr_pending_interrupt_include_p(target_th, err)) { return Qtrue; } else { return Qfalse; } } return Qtrue; } }
Returns the priority of thr. Default is inherited from the current thread which creating the new thread, or zero for the initial main thread; higher-priority thread will run more frequently than lower-priority threads (but lower-priority threads can also run).
This is just hint for Ruby thread scheduler. It may be ignored on some platform.
Thread.current.priority #=> 0
static VALUE rb_thread_priority(VALUE thread) { return INT2NUM(rb_thread_ptr(thread)->priority); }
Sets the priority of thr to integer. Higher-priority threads will run more frequently than lower-priority threads (but lower-priority threads can also run).
This is just hint for Ruby thread scheduler. It may be ignored on some platform.
count1 = count2 = 0 a = Thread.new do loop { count1 += 1 } end a.priority = -1 b = Thread.new do loop { count2 += 1 } end b.priority = -2 sleep 1 #=> 1 count1 #=> 622504 count2 #=> 5832
static VALUE rb_thread_priority_set(VALUE thread, VALUE prio) { rb_thread_t *target_th = rb_thread_ptr(thread); int priority; #if USE_NATIVE_THREAD_PRIORITY target_th->priority = NUM2INT(prio); native_thread_apply_priority(th); #else priority = NUM2INT(prio); if (priority > RUBY_THREAD_PRIORITY_MAX) { priority = RUBY_THREAD_PRIORITY_MAX; } else if (priority < RUBY_THREAD_PRIORITY_MIN) { priority = RUBY_THREAD_PRIORITY_MIN; } target_th->priority = priority; #endif return INT2NUM(target_th->priority); }
Raises an exception from the given thread. The caller does not have to be thr
. See Kernel#raise
for more information.
Thread.abort_on_exception = true a = Thread.new { sleep(200) } a.raise("Gotcha")
This will produce:
prog.rb:3: Gotcha (RuntimeError) from prog.rb:2:in `initialize' from prog.rb:2:in `new' from prog.rb:2
static VALUE thread_raise_m(int argc, VALUE *argv, VALUE self) { rb_thread_t *target_th = rb_thread_ptr(self); const rb_thread_t *current_th = GET_THREAD(); threadptr_check_pending_interrupt_queue(target_th); rb_threadptr_raise(target_th, argc, argv); /* To perform Thread.current.raise as Kernel.raise */ if (current_th == target_th) { RUBY_VM_CHECK_INTS(target_th->ec); } return Qnil; }
Returns the status of the thread-local “report on exception'' condition for this thr
.
The default value when creating a Thread
is the value of the global flag Thread.report_on_exception
.
See also report_on_exception=
.
There is also a class level method to set this for all new threads, see ::report_on_exception=
.
static VALUE rb_thread_report_exc(VALUE thread) { return rb_thread_ptr(thread)->report_on_exception ? Qtrue : Qfalse; }
When set to true
, a message is printed on $stderr if an exception kills this thr
. See ::report_on_exception
for details.
See also report_on_exception
.
There is also a class level method to set this for all new threads, see ::report_on_exception=
.
static VALUE rb_thread_report_exc_set(VALUE thread, VALUE val) { rb_thread_ptr(thread)->report_on_exception = RTEST(val); return val; }
Wakes up thr
, making it eligible for scheduling.
a = Thread.new { puts "a"; Thread.stop; puts "c" } sleep 0.1 while a.status!='sleep' puts "Got here" a.run a.join
This will produce:
a Got here c
See also the instance method wakeup
.
VALUE rb_thread_run(VALUE thread) { rb_thread_wakeup(thread); rb_thread_schedule(); return thread; }
Returns the safe level in effect for thr. Setting thread-local safe levels can help when implementing sandboxes which run insecure code.
thr = Thread.new { $SAFE = 1; sleep } Thread.current.safe_level #=> 0 thr.safe_level #=> 1
static VALUE rb_thread_safe_level(VALUE thread) { return INT2NUM(rb_thread_ptr(thread)->ec->safe_level); }
Establishes proc on thr as the handler for tracing, or disables tracing if the parameter is nil
.
static VALUE thread_set_trace_func_m(VALUE target_thread, VALUE trace) { rb_execution_context_t *ec = GET_EC(); rb_thread_t *target_th = rb_thread_ptr(target_thread); rb_threadptr_remove_event_hook(ec, target_th, call_trace_func, Qundef); if (NIL_P(trace)) { return Qnil; } else { thread_add_trace_func(ec, target_th, trace); return trace; } }
Returns the status of thr
.
"sleep"
Returned if this thread is sleeping or waiting on I/O
"run"
When this thread is executing
"aborting"
If this thread is aborting
false
When this thread is terminated normally
nil
If terminated with an exception.
a = Thread.new { raise("die now") } b = Thread.new { Thread.stop } c = Thread.new { Thread.exit } d = Thread.new { sleep } d.kill #=> #<Thread:0x401b3678 aborting> a.status #=> nil b.status #=> "sleep" c.status #=> false d.status #=> "aborting" Thread.current.status #=> "run"
See also the instance methods alive?
and stop?
static VALUE rb_thread_status(VALUE thread) { rb_thread_t *target_th = rb_thread_ptr(thread); if (rb_threadptr_dead(target_th)) { if (!NIL_P(target_th->ec->errinfo) && !FIXNUM_P(target_th->ec->errinfo)) { return Qnil; } else { return Qfalse; } } else { return rb_str_new2(thread_status_name(target_th, FALSE)); } }
Returns true
if thr
is dead or sleeping.
a = Thread.new { Thread.stop } b = Thread.current a.stop? #=> true b.stop? #=> false
static VALUE rb_thread_stop_p(VALUE thread) { rb_thread_t *th = rb_thread_ptr(thread); if (rb_threadptr_dead(th)) { return Qtrue; } else if (th->status == THREAD_STOPPED || th->status == THREAD_STOPPED_FOREVER) { return Qtrue; } else { return Qfalse; } }
Terminates thr
and schedules another thread to be run.
If this thread is already marked to be killed, exit
returns the Thread
.
If this is the main thread, or the last thread, exits the process.
VALUE rb_thread_kill(VALUE thread) { rb_thread_t *th = rb_thread_ptr(thread); if (th->to_kill || th->status == THREAD_KILLED) { return thread; } if (th == th->vm->main_thread) { rb_exit(EXIT_SUCCESS); } thread_debug("rb_thread_kill: %p (%"PRI_THREAD_ID")\n", (void *)th, thread_id_str(th)); if (th == GET_THREAD()) { /* kill myself immediately */ rb_threadptr_to_kill(th); } else { threadptr_check_pending_interrupt_queue(th); rb_threadptr_pending_interrupt_enque(th, eKillSignal); rb_threadptr_interrupt(th); } return thread; }
Returns true
if the given string (or symbol) exists as a thread-local variable.
me = Thread.current me.thread_variable_set(:oliver, "a") me.thread_variable?(:oliver) #=> true me.thread_variable?(:stanley) #=> false
Note that these are not fiber local variables. Please see Thread#[]
and Thread#thread_variable_get
for more details.
static VALUE rb_thread_variable_p(VALUE thread, VALUE key) { VALUE locals; ID id = rb_check_id(&key); if (!id) return Qfalse; locals = rb_ivar_get(thread, id_locals); if (!RHASH(locals)->ntbl) return Qfalse; if (st_lookup(RHASH(locals)->ntbl, ID2SYM(id), 0)) { return Qtrue; } return Qfalse; }
Returns the value of a thread local variable that has been set. Note that these are different than fiber local values. For fiber local values, please see Thread#[]
and Thread#[]=
.
Thread
local values are carried along with threads, and do not respect fibers. For example:
Thread.new { Thread.current.thread_variable_set("foo", "bar") # set a thread local Thread.current["foo"] = "bar" # set a fiber local Fiber.new { Fiber.yield [ Thread.current.thread_variable_get("foo"), # get the thread local Thread.current["foo"], # get the fiber local ] }.resume }.join.value # => ['bar', nil]
The value “bar” is returned for the thread local, where nil is returned for the fiber local. The fiber is executed in the same thread, so the thread local values are available.
static VALUE rb_thread_variable_get(VALUE thread, VALUE key) { VALUE locals; locals = rb_ivar_get(thread, id_locals); return rb_hash_aref(locals, rb_to_symbol(key)); }
Sets a thread local with key
to value
. Note that these are local to threads, and not to fibers. Please see Thread#thread_variable_get
and Thread#[]
for more information.
static VALUE rb_thread_variable_set(VALUE thread, VALUE id, VALUE val) { VALUE locals; if (OBJ_FROZEN(thread)) { rb_error_frozen("thread locals"); } locals = rb_ivar_get(thread, id_locals); return rb_hash_aset(locals, rb_to_symbol(id), val); }
Returns an array of the names of the thread-local variables (as Symbols).
thr = Thread.new do Thread.current.thread_variable_set(:cat, 'meow') Thread.current.thread_variable_set("dog", 'woof') end thr.join #=> #<Thread:0x401b3f10 dead> thr.thread_variables #=> [:dog, :cat]
Note that these are not fiber local variables. Please see Thread#[]
and Thread#thread_variable_get
for more details.
static VALUE rb_thread_variables(VALUE thread) { VALUE locals; VALUE ary; locals = rb_ivar_get(thread, id_locals); ary = rb_ary_new(); rb_hash_foreach(locals, keys_i, ary); return ary; }
Dump the name, id, and status of thr to a string.
static VALUE rb_thread_to_s(VALUE thread) { VALUE cname = rb_class_path(rb_obj_class(thread)); rb_thread_t *target_th = rb_thread_ptr(thread); const char *status; VALUE str; status = thread_status_name(target_th, TRUE); str = rb_sprintf("#<%"PRIsVALUE":%p", cname, (void *)thread); if (!NIL_P(target_th->name)) { rb_str_catf(str, "@%"PRIsVALUE, target_th->name); } if (!target_th->first_func && target_th->first_proc) { VALUE loc = rb_proc_location(target_th->first_proc); if (!NIL_P(loc)) { const VALUE *ptr = RARRAY_CONST_PTR(loc); rb_str_catf(str, "@%"PRIsVALUE":%"PRIsVALUE, ptr[0], ptr[1]); rb_gc_force_recycle(loc); } } rb_str_catf(str, " %s>", status); OBJ_INFECT(str, thread); return str; }
Waits for thr
to complete, using join
, and returns its value or raises the exception which terminated the thread.
a = Thread.new { 2 + 2 } a.value #=> 4 b = Thread.new { raise 'something went wrong' } b.value #=> RuntimeError: something went wrong
static VALUE thread_value(VALUE self) { rb_thread_t *th = rb_thread_ptr(self); thread_join(th, DELAY_INFTY); return th->value; }
Marks a given thread as eligible for scheduling, however it may still remain blocked on I/O.
Note: This does not invoke the scheduler, see run
for more information.
c = Thread.new { Thread.stop; puts "hey!" } sleep 0.1 while c.status!='sleep' c.wakeup c.join #=> "hey!"
VALUE rb_thread_wakeup(VALUE thread) { if (!RTEST(rb_thread_wakeup_alive(thread))) { rb_raise(rb_eThreadError, "killed thread"); } return thread; }