Date: Fri, 19 Nov 1999 10:18:22 -0800 From: "Scott Hess" <scott@avantgo.com> To: "Daniel Eischen" <eischen@vigrid.com>, <freebsd-hackers@FreeBSD.ORG> Subject: Re: EINTR problems with multithreaded programs. Message-ID: <03e501bf32ba$76d83550$1e80000a@avantgo.com> References: <199911191814.NAA02164@pcnet1.pcnet.com>
next in thread | previous in thread | raw e-mail | index | archive | help
This is a multi-part message in MIME format.
------=_NextPart_000_03E2_01BF3277.68A11F30
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: 7bit
Daniel Eischen <eischen@vigrid.com> wrote:
>Scott Hess mailto:scott@avantgo.com wrote:
> > When using -pthread on FreeBSD3.3 to build a multithreaded program, I
find
> > that signals are delivered to all threads (see attached program).
> > Specifically, if multiple threads are in blocking read calls, and a
signal
> > is handled, they will all receive -1 from the read and EINTR in errno.
>
> If you don't want all threads to see the signal(s), then you
> have to block the signal(s) in each thread.
I've checked further, and found that FreeBSD correctly handles blocking
signals on a per-thread basis. _But_, all threads still get EINTR when a
signal happens while they're in a blocking read.
I've attached the updated program that shows the correct delivery of the
signals, with system calls still being interrupted. [Sorry about the
attachment, but that seems the safest way to go about getting the file
delivered in usable fashion.]
Thanks,
scott
------=_NextPart_000_03E2_01BF3277.68A11F30
Content-Type: application/octet-stream;
name="thread_EINTR.c"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: attachment;
filename="thread_EINTR.c"
#include <pthread.h>=0A=
#include <errno.h>=0A=
#include <sys/types.h>=0A=
#include <signal.h>=0A=
=0A=
static void signal_handler( int sig)=0A=
{=0A=
printf( "%p Got signal %d\n", pthread_self(), sig);=0A=
}=0A=
=0A=
static void *reader( void *arg)=0A=
{=0A=
char buf[ 1024];=0A=
int cc;=0A=
int ii=3D(int)arg;=0A=
int fd=3Ddup( 0);=0A=
sigset_t set;=0A=
=0A=
sigemptyset( &set);=0A=
if( (ii%3)=3D=3D0 || (ii%3)=3D=3D1) {=0A=
sigaddset( &set, SIGUSR1);=0A=
}=0A=
if( (ii%3)=3D=3D0 || (ii%3)=3D=3D2) {=0A=
sigaddset( &set, SIGUSR2);=0A=
}=0A=
pthread_sigmask( SIG_BLOCK, &set, NULL);=0A=
=0A=
{=0A=
struct sigaction sa_usr1=3D{ signal_handler, 0, SA_RESTART};=0A=
struct sigaction sa_usr2=3D{ signal_handler, 0, SA_RESTART};=0A=
sigaction( SIGUSR1, &sa_usr1, NULL);=0A=
sigaction( SIGUSR2, &sa_usr2, NULL);=0A=
}=0A=
=0A=
printf( "%p/%d waiting for data\n", pthread_self(), ii);=0A=
while(1) {=0A=
cc=3Dread( fd, buf, sizeof( buf));=0A=
if( cc>=3D0) {=0A=
printf( "%p got %d bytes\n", pthread_self(), cc);=0A=
} else {=0A=
printf( "%p saw errno=3D=3D%d/%s\n", pthread_self(), errno, =
strerror( errno));=0A=
}=0A=
}=0A=
return NULL;=0A=
}=0A=
=0A=
void main( void)=0A=
{=0A=
int ii, cc=3D9;=0A=
pthread_t child;=0A=
=0A=
#if 0=0A=
signal( SIGUSR1, signal_handler);=0A=
#else=0A=
{=0A=
struct sigaction sa_usr1=3D{ signal_handler, 0, SA_RESTART};=0A=
struct sigaction sa_usr2=3D{ signal_handler, 0, SA_RESTART};=0A=
sigaction( SIGUSR1, &sa_usr1, NULL);=0A=
sigaction( SIGUSR2, &sa_usr2, NULL);=0A=
}=0A=
#endif=0A=
=0A=
for( ii=3D0; ii<cc; ii++) {=0A=
if( pthread_create( &child, NULL, reader, (void *)ii)) {=0A=
perror( "spawning thread");=0A=
exit( 1);=0A=
}=0A=
}=0A=
while( 1) {=0A=
sleep( 2);=0A=
kill( getpid(), SIGUSR1);=0A=
sleep( 2);=0A=
kill( getpid(), SIGUSR2);=0A=
}=0A=
exit( 0);=0A=
}=0A=
------=_NextPart_000_03E2_01BF3277.68A11F30--
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?03e501bf32ba$76d83550$1e80000a>