X-Recipient:	archive-cygwin AT delorie DOT com
DKIM-Filter:	OpenDKIM Filter v2.11.0 sourceware.org 48A6238708D3
DKIM-Signature:	v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
	s=default; t=1610216624;
	bh=C+49JTNRSm1VUw0wnYUTyeT4GvswnOMUuLTThgdYfTo=;
	h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post:
	List-Help:List-Subscribe:From:Reply-To:From;
	b=V7burmxrdzNTF4EGWSRYGUoZue5KY47DHzBKHdqjvKiQVF33JtGQUOz86MXr0H2Ld
	cmtYRXRKLVBQsWqRKZrm/C/ao28IaWzv4NF9bGvK6CcLANf2KvqBOImMAHtf42suCM
	DvqFP4nSUmXgTmBIi5b/D6fWszcnQbe948An2PaY=
X-Original-To:	cygwin AT cygwin DOT com
Delivered-To:	cygwin AT cygwin DOT com
DMARC-Filter:	OpenDMARC Filter v1.3.2 sourceware.org 0718138708C0
To:	"cygwin AT cygwin DOT com" <cygwin AT cygwin DOT com>
Subject:	PTHREAD_MUTEX_SHARED on Cygwin
Message-ID:	<657c8576-2715-8c80-a59a-23453306230f@netcologne.de>
Date:	Sat, 9 Jan 2021 19:23:39 +0100
User-Agent:	Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
	Thunderbird/78.6.0
MIME-Version:	1.0
X-Spam-Status:	No, score=-3.8 required=5.0 tests=BAYES_00, DKIM_SIGNED,
	DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE,
	SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2
X-Spam-Checker-Version:	SpamAssassin 3.4.2 (2018-09-13) on
	server2.sourceware.org
X-BeenThere:	cygwin AT cygwin DOT com
X-Mailman-Version:	2.1.29
List-Id:	General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Archive:	<https://cygwin.com/pipermail/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe:	<https://cygwin.com/mailman/listinfo/cygwin>,
	<mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From:	Thomas Koenig via Cygwin <cygwin AT cygwin DOT com>
Reply-To:	Thomas Koenig <tkoenig AT netcologne DOT de>
Sender:	"Cygwin" <cygwin-bounces AT cygwin DOT com>

This is a multi-part message in MIME format.
--------------EAE2AEE4CB4327D20C84C5FF
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit


Hi,

there is a branch of gfortran for implementing coarrays based on a
shared memory implementation instead of MPI, the devel_coarray/native
branch.

I tried it out on Cygwin, but it doesn't work there (hangs on the
first sync).

The branch uses pthread mutexes and condition variables
with PTHREAD_PROCESS_SHARED for synchronization between processes.

I also ran the attached test program, which gave the output

pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED)failed: No error


Is it correct that PTHREAD_PROCESS_SHARED is not supported on
Cygwin?  Is it supported for condition variables, or is the fact
that it is reported as working an oversight?

If PTHREAD_PROCESS_SHARED does not work, are there known workarounds?

Best regards

	Thomas

--------------EAE2AEE4CB4327D20C84C5FF
Content-Type: text/x-csrc; charset=UTF-8;
 name="s.c"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment;
 filename="s.c"

#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <unistd.h>

#define ERR_CHK(x) \
  do { \
	if (x) { \
	  perror(#x "failed"); \
	  exit(1); \
	} \
  } while (0)

int
main(int argc, char **argv) {
  pthread_condattr_t cattr;
  pthread_mutexattr_t mattr;
  pthread_mutex_t *m;
  pthread_cond_t *c;
  void *mem;

  ERR_CHK((mem = mmap(0, 0x1000, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0)) == MAP_FAILED);

  m = mem;
  c = mem + 0x800;

  ERR_CHK(pthread_mutexattr_init(&mattr));
  ERR_CHK(pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED));
  ERR_CHK(pthread_mutex_init(m, &mattr));
  ERR_CHK(pthread_mutexattr_destroy(&mattr));

  ERR_CHK(pthread_condattr_init(&cattr));
  ERR_CHK(pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED));
  ERR_CHK(pthread_cond_init(c, &cattr));
  ERR_CHK(pthread_condattr_destroy(&cattr));

  printf("Success\n");

  return 0;
}

--------------EAE2AEE4CB4327D20C84C5FF
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

--
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple

--------------EAE2AEE4CB4327D20C84C5FF--

- Raw text -