libstdc++/10193: Regression: iostreams no longer threadsafe

[peturr02@ru.is]

>Number:         10193
>Category:       libstdc++
>Synopsis:       Regression: iostreams no longer threadsafe
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 23 19:26:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     peturr02@ru.is
>Release:        gcc-3.2.2
>Organization:
>Environment:
Red Hat Linux 8.0
>Description:
The iostreams implementation in gcc-2.95.x was reasonably threadsafe, as is stdio on glibc-2.3. The implementation of iostreams in gcc-3.x is however not threadsafe at all.
>How-To-Repeat:
See attachment.
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: text/plain; name="threadbug.cc"
Content-Disposition: inline; filename="threadbug.cc"

#include <iostream>
#include <sstream>
#include <vector>
#include <cstdlib>

#include <unistd.h>
#include <pthread.h>

void* thread(void* p)
{
	using namespace std;
	int n = *static_cast<int*>(p);

	for (;;)
	{
		ostringstream stream;
		stream << "thread" << n << '\n';
		clog << stream.str();
	}

	return 0;
}

struct threadstuff
{
	pthread_t t;
	int n;
};

int main(int argc, char** argv)
{
	using namespace std;

	int numthreads = 10;
	if (argc > 1)
		numthreads = atoi(argv[1]);

	vector<threadstuff> vec (numthreads);

	pthread_attr_t attr;
	pthread_attr_init(&attr);

	for (int i = 0; i < numthreads; ++i)
	{
		vec[i].n = i;
		pthread_create(&vec[i].t, &attr, &thread, &vec[i].n);
	}

	sleep(10);
	return 0;
}