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digitalmars.D - SIGUSR1 Makes Program Hang?

reply teqDruid <me teqdruid.com> writes:
I've been having an issue with the XML-RPC stuff I'm doing with Mango. 
The libraries being used are phobos, mango, and Andy's XML parser, in
addition to my XmlRpc code.  I'm using DMD 0.98 on Linux.

Kris and I have been trying to figure out what's going on. (the
discussion is at: http://dsource.org/forums/viewtopic.php?t=338 if
you want to follow along)
We've narrowed it down using some strace output, and we think this is
causing the melt-down:
kill(6228, SIGUSR1) = 0
followed by:
rt_sigprocmask(SIG_SETMASK, NULL, [RTMIN], 8) = 0
rt_sigsuspend([]--- SIGRTMIN (Unknown signal 32)   0 (0) ---
) = -1 EINTR (Interrupted system call)
sigreturn()                             = ? (mask now [RTMIN])
rt_sigprocmask(SIG_SETMASK, NULL, [RTMIN], 8) = 0
rt_sigsuspend([]+++ killed by SIGKILL +++

The "killed by SIGKILL" is me doing a killall -s KILL, since that's the
only way to kill it.  At this point in program execution, a certain number
of POST requests have been made at the server, each one being sent after
each reply.  At this point there appears to be 3 processes.  3228 is the
main thread which launched the mango HTTP server.  It waits for me to hit
enter, then dies, and takes everything else with it. (this is the
"correct" behavoir".) There's PID 3229, which I think is the listener
thread, then there's 3230 (which I think is a worker thread), from which
the strace output above is from.

Once that kill is run by that process (at least we think that's the point
it's occuring at) everything seems to hang.  The server won't accept
connections, and the main thread won't die when I hit enter.

Here's what I don't know:
What's running the kill.  Why it's being run after a certain number of
requests.  Why a SIGUSR1 at the main process causes everything to hang.
BTW, the number of the requests seems to vary with what code is
running... if I comment out a line or two the number changes, although I
haven't been able to pick out a pattern.  It's been bloody impossible for
me to figure out what code is causing this, because everytime I comment
out some code, or put in some debug code, the point at which everything
dies changes.

Does anyone have any suggestions or possible leads?  (Please)

John
Sep 06 2004
next sibling parent reply Ben Hinkle <bhinkle4 juno.com> writes:
teqDruid wrote:

 I've been having an issue with the XML-RPC stuff I'm doing with Mango.
 The libraries being used are phobos, mango, and Andy's XML parser, in
 addition to my XmlRpc code.  I'm using DMD 0.98 on Linux.
 
 Kris and I have been trying to figure out what's going on. (the
 discussion is at: http://dsource.org/forums/viewtopic.php?t=338 if
 you want to follow along)
 We've narrowed it down using some strace output, and we think this is
 causing the melt-down:
 kill(6228, SIGUSR1) = 0
 followed by:
 rt_sigprocmask(SIG_SETMASK, NULL, [RTMIN], 8) = 0
 rt_sigsuspend([]--- SIGRTMIN (Unknown signal 32)   0 (0) ---
 ) = -1 EINTR (Interrupted system call)
 sigreturn()                             = ? (mask now [RTMIN])
 rt_sigprocmask(SIG_SETMASK, NULL, [RTMIN], 8) = 0
 rt_sigsuspend([]+++ killed by SIGKILL +++
 
 The "killed by SIGKILL" is me doing a killall -s KILL, since that's the
 only way to kill it.  At this point in program execution, a certain number
 of POST requests have been made at the server, each one being sent after
 each reply.  At this point there appears to be 3 processes.  3228 is the
 main thread which launched the mango HTTP server.  It waits for me to hit
 enter, then dies, and takes everything else with it. (this is the
 "correct" behavoir".) There's PID 3229, which I think is the listener
 thread, then there's 3230 (which I think is a worker thread), from which
 the strace output above is from.
 
 Once that kill is run by that process (at least we think that's the point
 it's occuring at) everything seems to hang.  The server won't accept
 connections, and the main thread won't die when I hit enter.
 
 Here's what I don't know:
 What's running the kill.  Why it's being run after a certain number of
 requests.  Why a SIGUSR1 at the main process causes everything to hang.
 BTW, the number of the requests seems to vary with what code is
 running... if I comment out a line or two the number changes, although I
 haven't been able to pick out a pattern.  It's been bloody impossible for
 me to figure out what code is causing this, because everytime I comment
 out some code, or put in some debug code, the point at which everything
 dies changes.
 
 Does anyone have any suggestions or possible leads?  (Please)
 
 John

I just checked and std.thread installs SIGUSER1 and SIGUSER2 handlers for thread pausing and resuming.
Sep 06 2004
parent reply "antiAlias" <fu bar.com> writes:
"Ben Hinkle" <bhinkle4 juno.com>
I just checked and std.thread installs SIGUSER1 and SIGUSER2 handlers for
thread pausing and resuming.

==================

I have a sneaking suspicion that the GC paused that thread. What do you
think, Ben?
Sep 06 2004
parent reply teqDruid <me teqdruid.com> writes:
On Mon, 06 Sep 2004 21:02:15 -0700, antiAlias wrote:

 "Ben Hinkle" <bhinkle4 juno.com>
 I just checked and std.thread installs SIGUSER1 and SIGUSER2 handlers for
 thread pausing and resuming.
 
 ==================
 
 I have a sneaking suspicion that the GC paused that thread. What do you
 think, Ben?

I did a: std.gc.disable(); at the start of the program. No effect. I'm assuming that one doesn't have to call this in each thread.
Sep 06 2004
parent reply Ben Hinkle <bhinkle4 juno.com> writes:
teqDruid wrote:

 On Mon, 06 Sep 2004 21:02:15 -0700, antiAlias wrote:
 
 "Ben Hinkle" <bhinkle4 juno.com>
 I just checked and std.thread installs SIGUSER1 and SIGUSER2 handlers for
 thread pausing and resuming.
 
 ==================
 
 I have a sneaking suspicion that the GC paused that thread. What do you
 think, Ben?

I did a: std.gc.disable(); at the start of the program. No effect. I'm assuming that one doesn't have to call this in each thread.

interestingly enough I looked at internal/gc/gcx.d and calling disable() doesn't seem to actually disable the gc. It sets the flag but the flag is never checked.
Sep 07 2004
parent reply teqDruid <me teqdruid.com> writes:
OK... so how does one disable the GC?  Is it even possible, Walter?

John

On Tue, 07 Sep 2004 12:30:34 -0400, Ben Hinkle wrote:

 teqDruid wrote:
 
 On Mon, 06 Sep 2004 21:02:15 -0700, antiAlias wrote:
 
 "Ben Hinkle" <bhinkle4 juno.com>
 I just checked and std.thread installs SIGUSER1 and SIGUSER2 handlers for
 thread pausing and resuming.
 
 ==================
 
 I have a sneaking suspicion that the GC paused that thread. What do you
 think, Ben?

I did a: std.gc.disable(); at the start of the program. No effect. I'm assuming that one doesn't have to call this in each thread.

interestingly enough I looked at internal/gc/gcx.d and calling disable() doesn't seem to actually disable the gc. It sets the flag but the flag is never checked.

Sep 07 2004
parent "Walter" <newshound digitalmars.com> writes:
It's just not implemented yet :-( the function is there for future use.

"teqDruid" <me teqdruid.com> wrote in message
news:pan.2004.09.07.19.49.52.444734 teqdruid.com...
 OK... so how does one disable the GC?  Is it even possible, Walter?

 John

 On Tue, 07 Sep 2004 12:30:34 -0400, Ben Hinkle wrote:

 teqDruid wrote:

 On Mon, 06 Sep 2004 21:02:15 -0700, antiAlias wrote:

 "Ben Hinkle" <bhinkle4 juno.com>
 I just checked and std.thread installs SIGUSER1 and SIGUSER2 handlers




 thread pausing and resuming.

 ==================

 I have a sneaking suspicion that the GC paused that thread. What do




 think, Ben?

I did a: std.gc.disable(); at the start of the program. No effect. I'm assuming that one doesn't have to call this in each thread.

interestingly enough I looked at internal/gc/gcx.d and calling disable() doesn't seem to actually disable the gc. It sets the flag but the flag


 never checked.


Sep 10 2004
prev sibling parent Dave <Dave_member pathlink.com> writes:
Bare in mind I don't know anything about Mango and the rest, but in
phobos/std/thread.d SIGUSR1 is trapped to pause a thread.

Maybe one of the processes is doing a pthread_kill(tid,SIGUSR1) to pause the
main thread as part of the socket polling process?

Just a thought..

- Dave

In article <pan.2004.09.07.01.04.06.41323 teqdruid.com>, teqDruid says...
I've been having an issue with the XML-RPC stuff I'm doing with Mango. 
The libraries being used are phobos, mango, and Andy's XML parser, in
addition to my XmlRpc code.  I'm using DMD 0.98 on Linux.

Kris and I have been trying to figure out what's going on. (the
discussion is at: http://dsource.org/forums/viewtopic.php?t=338 if
you want to follow along)
We've narrowed it down using some strace output, and we think this is
causing the melt-down:
kill(6228, SIGUSR1) = 0
followed by:
rt_sigprocmask(SIG_SETMASK, NULL, [RTMIN], 8) = 0
rt_sigsuspend([]--- SIGRTMIN (Unknown signal 32)   0 (0) ---
) = -1 EINTR (Interrupted system call)
sigreturn()                             = ? (mask now [RTMIN])
rt_sigprocmask(SIG_SETMASK, NULL, [RTMIN], 8) = 0
rt_sigsuspend([]+++ killed by SIGKILL +++

The "killed by SIGKILL" is me doing a killall -s KILL, since that's the
only way to kill it.  At this point in program execution, a certain number
of POST requests have been made at the server, each one being sent after
each reply.  At this point there appears to be 3 processes.  3228 is the
main thread which launched the mango HTTP server.  It waits for me to hit
enter, then dies, and takes everything else with it. (this is the
"correct" behavoir".) There's PID 3229, which I think is the listener
thread, then there's 3230 (which I think is a worker thread), from which
the strace output above is from.

Once that kill is run by that process (at least we think that's the point
it's occuring at) everything seems to hang.  The server won't accept
connections, and the main thread won't die when I hit enter.

Here's what I don't know:
What's running the kill.  Why it's being run after a certain number of
requests.  Why a SIGUSR1 at the main process causes everything to hang.
BTW, the number of the requests seems to vary with what code is
running... if I comment out a line or two the number changes, although I
haven't been able to pick out a pattern.  It's been bloody impossible for
me to figure out what code is causing this, because everytime I comment
out some code, or put in some debug code, the point at which everything
dies changes.

Does anyone have any suggestions or possible leads?  (Please)

John

Sep 06 2004