diff options
Diffstat (limited to 'doc/Thread.3')
| -rw-r--r-- | doc/Thread.3 | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/doc/Thread.3 b/doc/Thread.3 index 59bf488..2005c93 100644 --- a/doc/Thread.3 +++ b/doc/Thread.3 @@ -137,17 +137,17 @@ Tcl provides \fBTcl_ThreadQueueEvent\fR and \fBTcl_ThreadAlert\fR for handling event queuing in multithreaded applications. See the \fBNotifier\fR manual page for more information on these procedures. .PP -A mutex is a -.VS TIP509 -recursive -.VE TIP509 -lock that is used to serialize all threads through a piece +A mutex is a lock that is used to serialize all threads through a piece of code by calling \fBTcl_MutexLock\fR and \fBTcl_MutexUnlock\fR. If one thread holds a mutex, any other thread calling \fBTcl_MutexLock\fR will block until \fBTcl_MutexUnlock\fR is called. A mutex can be destroyed after its use by calling \fBTcl_MutexFinalize\fR. -The result of locking a mutex twice from the same thread is undefined. -On some platforms it will result in a deadlock. +.VS TIP509 +Mutexes are reentrant: they can be locked several times from the same +thread. However there must be exactly one call to +\fBTcl_MutexUnlock\fR for each call to \fBTcl_MutexLock\fR in order +for a thread to release a mutex completely. +.VE TIP509 The \fBTcl_MutexLock\fR, \fBTcl_MutexUnlock\fR and \fBTcl_MutexFinalize\fR procedures are defined as empty macros if not compiling with threads enabled. For declaration of mutexes the \fBTCL_DECLARE_MUTEX\fR macro should be used. |