How to sleep and wake a thread??? Post: 302582627

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Top Forums Programming How to sleep and wake a thread??? Post 302582627 by DreamWarrior on Friday 16th of December 2011 02:59:14 PM

12-16-2011

Registered User

Quote:

Originally Posted by jim mcnamara

As John said above, you probably want your thread to block not sleep. Calls like sleep send SIGALRM to the calling process, not just the thread. This means that you have to set up signal handling for the thread in question, and have all the other threads ignore
SIGALRM (example only, there are other signals)

Using a condition wait or a mutex wait is much more efficient.

sleep doesn't send SIGALRM.

At any rate, pause will work, I've seen people do:

Code:

for ( ; ; ) sleep(UINT_MAX);

And then, as mentioned, pthread_kill can wake it provided the thread hasn't blocked the signal.

Also, as mentioned, there is no way for another thread to cause someone to "go to sleep".

For your edification, this seems like a simple producer-consumer model, and that's usually handled with condition variables. See: pthread_cond_init, pthread_cond_wait, and pthread_cond_signal.

DreamWarrior

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assert_wait_mesg

assert_wait_mesg(9r)													      assert_wait_mesg(9r)

NAME

       assert_wait_mesg - General: Asserts that the current kernel thread is about to block (sleep)

SYNOPSIS

       void assert_wait_mesg(
	       vm_offset_t event,
	       boolean_t interruptible,
	       char *message );

ARGUMENTS

       Specifies the event associated with the current kernel thread.  Specifies a Boolean value that indicates how the kernel thread is awakened.
       You can pass one of the following values: The current kernel thread is interruptible. This value means that a signal can awaken the current
       kernel  thread.	The current kernel thread is not interruptible. This value means that only the specified event can awaken the current ker-
       nel thread.  Specifies a mnemonic for the type of wait. The ps command uses this mnemonic to print out more  meaningful	messages  about  a
       process.

DESCRIPTION

       The assert_wait_mesgroutine asserts that the current kernel thread is about to block (sleep) until the specified event occurs. This routine
       sets a thread wait bit in the pointer to the thread structure associated with the current kernel thread.  This bit signifies that this ker-
       nel thread is on the appropriate wait hash queue, waiting for a wakeup call.

       To actually block (put to sleep) the current kernel thread, call thread_block.

       To issue a wakeup call on the specified event, call the thread_wakeup_prim or clear_wait routine.

CAUTIONS

       You  must  not call assert_wait_mesg from a device driver's interrupt handler. The reason for this is that at interrupt context there is no
       process to be put to sleep.

RETURN VALUES

       None

SEE ALSO

       Data Structures: thread(9s)

       Routines: clear_wait(9r), current_thread(9r), thread_block(9r)

       Reference Pages Section 1: ps

															      assert_wait_mesg(9r)