05-30-2011
Quote:
Originally Posted by
scubanarc
I think that Corona has it right. At least that's my understanding.
So the real heart of the question is whether or not a single socket can be used for blocking and sending at the same time. Has anyone attempted this? We are having strange issues when doing it, like seg faults.
We're doing that without any problem. We have one thread that blocks on the socket waiting for the server to send data; while another thread might independently send some data to the server. Works like a charm.
As mentioned By Coronna688, the best way for you to identify the problem (and for us to help you) is to write a minimalistic example - that compiles and show what your problem is.
Good Luck,
Loïc
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LEARN ABOUT OSF1
pthread_rwlock_wrlock
pthread_rwlock_wrlock(3) Library Functions Manual pthread_rwlock_wrlock(3)
NAME
pthread_rwlock_wrlock - Acquires a read-write lock for write access.
LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so)
SYNOPSIS
#include <pthread.h>
int pthread_rwlock_wrlock(
pthread_rwlock_t *rwlock);
PARAMETERS
Address of the read-write lock object to acquire for write access.
DESCRIPTION
This routine attempts to acquire a read-write lock for write access. If any thread already has acquired the lock for write access or read
access, the lock is not granted and the calling thread blocks until it can acquire the lock. A thread can hold only one lock for write
access on a read-write lock.
Results are undefined if the calling thread holds the read-write lock (whether for read or write access) at the time this routine is
called.
If the read-write lock object referenced by rwlock is not initialized, the results of calling this routine are undefined.
If a thread is interrupted (via a Tru64 UNIX signal or an OpenVMS AST) while waiting for a read-write lock for write access, upon return
from the interrupt routine the thread resumes waiting for the lock as if it had not been interrupted.
Realtime applications can encounter priority inversion when using read-write locks. The problem occurs when a high-priority thread acquires
a read-write lock that is about to be unlocked (that is, posted) by a low-priority thread, but the low-priority thread is preempted by a
medium-priority thread. This scenario leads to priority inversion in that a high-priority thread is blocked by lower-priority threads for
an unlimited period of time. During system design, realtime programmers must take into account the possibility of priority inversion and
can deal with it in a number of ways, such as by having critical sections that are guarded by read-write locks execute at a high priority,
so that a thread cannot be preempted while executing in its critical section.
RETURN VALUES
If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows:
Successful completion. The current thread already owns the read-write lock for write or read access. The value specified by rwlock does
not refer to an initialized read-write lock object.
ERRORS
None
RELATED INFORMATION
Functions: pthread_rwlock_init(3), pthread_rwlockattr_init(3), pthread_rwlock_rdlock(3), pthread_rwlock_trywrlock(3),
pthread_rwlock_unlock(3)
Manuals: Guide to DECthreads and Programmer's Guide
delim off
pthread_rwlock_wrlock(3)