Re: SIGCHLD SIG_IGN, then wait - warning messages
This patch worked for me, and it worked for the person
that posted the bug. No more warnings after applying
this patch.
I'm not sure what the procedure is for this, but I'd like
to request that this patch be committed so it will be
in future rsync versions.
Thanks Wayne!
--
Hardy Merrill
Red Hat, Inc.
Wayne Davison [EMAIL PROTECTED] wrote:
On Thu, Jul 24, 2003 at 09:09:48AM -0400, Hardy Merrill wrote:
What is the status on this?
I finally educated myself on this issue, and would like to propose a
patch. Since there are reports that zombies can get created when using
SIG_IGN on FreeBSD as well as other unices, I think we should change the
code to catch the signal and cleanup the zombies in the signal handler.
This would make the code similar to the handling in main.c.
..wayne..
--- socket.c 27 Jan 2003 03:35:09 - 1.84
+++ socket.c 24 Jul 2003 19:25:05 -
@@ -374,6 +374,14 @@
}
+static RETSIGTYPE sigchld_handler(int UNUSED(val)) {
+ signal(SIGCHLD, sigchld_handler);
+#ifdef WNOHANG
+ while (waitpid(-1, NULL, WNOHANG) 0) {}
+#endif
+}
+
+
void start_accept_loop(int port, int (*fn)(int, int))
{
int s;
@@ -419,14 +427,7 @@
if (fd == -1) continue;
- signal(SIGCHLD, SIG_IGN);
-
- /* we shouldn't have any children left hanging around
-but I have had reports that on Digital Unix zombies
-are produced, so this ensures that they are reaped */
-#ifdef WNOHANG
-while (waitpid(-1, NULL, WNOHANG) 0);
-#endif
+ signal(SIGCHLD, sigchld_handler);
if ((pid = fork()) == 0) {
int ret;
--
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Re: SIGCHLD SIG_IGN, then wait - warning messages
On Mon, Aug 04, 2003 at 10:53:36AM -0400, Hardy Merrill wrote: I'm not sure what the procedure is for this, but I'd like to request that this patch be committed so it will be in future rsync versions. I think it's at least better than what's currently there, so I've committed it to CVS. ..wayne.. -- To unsubscribe or change options: http://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
Re: SIGCHLD SIG_IGN, then wait - warning messages
What is the status on this? Is it being considered, or just ignored? Some (any) response would be appreciated :) If access to the bug is an issue, I can attach it - just let me know. Thanks. -- Hardy Merrill Red Hat, Inc. Hardy Merrill [EMAIL PROTECTED] wrote: Rsync maintainers please review rsync bug https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=98740 The code in question is in socket.c in start_accept_loop. The user is getting these warning messages: - Jul 8 12:56:59 ftp kernel: application bug: rsync(1051) has SIGCHLD set to SIG_IGN but calls wait(). Jul 8 12:56:59 ftp kernel: (see the NOTES section of 'man 2 wait'). Workaround activated. - I was able to reproduce that error with rsync server and client on Red Hat OS's on a fairly consistent basis by running an rsync server (rsync version 2.5.6 protocol version 27 from cvs 7/14) from the command line (rsync --daemon), and connecting with an rsync-2.4.6 client with this command: rsync -avv my.server.com::test/one /tmp/rsync_test I also produced the same error by using the same command from an rsync-2.5.6 protocol version 26 client. Here is my /etc/rsyncd.conf file: - log file = /var/log/rsync [test] uid = rsync1 gid = rsync1 path = /rsync_test comment = Rsync Test - Comment - Quoting one of the bug messages, These messages are a warning that rsync is not standards compliant with respect to its handling of child processes. According to POSIX (3.3.1.3) it is unspecified what happens when SIGCHLD is set to SIG_IGN. This code in socket.c: - signal(SIGCHLD, SIG_IGN); /* we shouldn't have any children left hanging around but I have had reports that on Digital Unix zombies are produced, so this ensures that they are reaped */ #ifdef WNOHANG while (waitpid(-1, NULL, WNOHANG) 0); #endif - sets SIGCHLD to SIG_IGN, and *then* waits if WNOHANG is defined. It would appear that if there are still children left to be cleaned up in Digital Unix after setting SIGCHLD to SIG_IGN, that there might be a bug in Digital Unix that rsync is coding a fix for. One coding change could be to change the #ifdef WNOHANG to a #ifdef Digital Unix string, so that only Digital Unix OS's would include and execute the waitpid. This would stop warning messages from being produced. Thanks. -- Hardy Merrill Red Hat, Inc. -- To unsubscribe or change options: http://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html -- To unsubscribe or change options: http://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
Re: SIGCHLD SIG_IGN, then wait - warning messages
On Thu, Jul 24, 2003 at 09:09:48AM -0400, Hardy Merrill wrote: What is the status on this? Is it being considered, or just ignored? Some (any) response would be appreciated :) If access to the bug is an issue, I can attach it - just let me know. Thanks. -- Hardy Merrill Red Hat, Inc. Hardy Merrill [EMAIL PROTECTED] wrote: Rsync maintainers please review rsync bug https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=98740 The code in question is in socket.c in start_accept_loop. The user is getting these warning messages: - Jul 8 12:56:59 ftp kernel: application bug: rsync(1051) has SIGCHLD set to SIG_IGN but calls wait(). Jul 8 12:56:59 ftp kernel: (see the NOTES section of 'man 2 wait'). Workaround activated. - I was able to reproduce that error with rsync server and client on Red Hat OS's on a fairly consistent basis by running an rsync server (rsync version 2.5.6 protocol version 27 from cvs 7/14) from the command line (rsync --daemon), and connecting with an rsync-2.4.6 client with this command: rsync -avv my.server.com::test/one /tmp/rsync_test I also produced the same error by using the same command from an rsync-2.5.6 protocol version 26 client. Here is my /etc/rsyncd.conf file: - log file = /var/log/rsync [test] uid = rsync1 gid = rsync1 path = /rsync_test comment = Rsync Test - Comment - Quoting one of the bug messages, These messages are a warning that rsync is not standards compliant with respect to its handling of child processes. According to POSIX (3.3.1.3) it is unspecified what happens when SIGCHLD is set to SIG_IGN. My wait(2) manpage reads: | NOTES | The Single Unix Specification describes a flag | SA_NOCLDÂWAIT (not supported under Linux) such that if | either this flag is set, or the action for SIGCHLD is set to | SIG_IGN (which, by the way, is not allowed by POSIX), then | children that exit do not become zombies and a call to | wait() or waitpid() will block until all children have | exited, and then fail with errno set to ECHILD. This looks like the behaviour is defined in the manpage it is only POSIX that has a problem with it. In fact the NOTES indicate that the Linux kernel is not POSIX compliant on this point. POSIX is obsolete as a standard, if it could ever be said to have qualified as one. Please refer to SUSv3 for any issues regarding standards compliance. Per SUSv3 and IEEE Std 1003.1, 2003 Edition regarding setting SIGCHLD to SIG_IGN: | If the action for the SIGCHLD signal is set to SIG_IGN, | child processes of the calling processes shall not be | transformed into zombie processes when they terminate. and regarding calling wait under those conditions: | If the calling process has SA_NOCLDWAIT set or has SIGCHLD | set to SIG_IGN, and the process has no unwaited-for children | that were transformed into zombie processes, the calling | thread shall block until all of the children of the process | containing the calling thread terminate, and wait() and | waitpid() shall fail and set errno to [ECHILD] This code in socket.c: - signal(SIGCHLD, SIG_IGN); /* we shouldn't have any children left hanging around but I have had reports that on Digital Unix zombies are produced, so this ensures that they are reaped */ #ifdef WNOHANG while (waitpid(-1, NULL, WNOHANG) 0); #endif - sets SIGCHLD to SIG_IGN, and *then* waits if WNOHANG is defined. It would appear that if there are still children left to be cleaned up in Digital Unix after setting SIGCHLD to SIG_IGN, that there might be a bug in Digital Unix that rsync is coding a fix for. This code is within the scope of compliance for current standards. If you have a specific patch that reorders these and still fixes the Digital UNIX bug i'll consider it but i this is not a priority. One coding change could be to change the #ifdef WNOHANG to a #ifdef Digital Unix string, so that only Digital Unix Absolutely not. The conditional compilation is
Re: SIGCHLD SIG_IGN, then wait - warning messages
On Thu, Jul 24, 2003 at 12:27:04PM -0700, Wayne Davison wrote:
On Thu, Jul 24, 2003 at 09:09:48AM -0400, Hardy Merrill wrote:
What is the status on this?
I finally educated myself on this issue, and would like to propose a
patch. Since there are reports that zombies can get created when using
SIG_IGN on FreeBSD as well as other unices, I think we should change the
code to catch the signal and cleanup the zombies in the signal handler.
This would make the code similar to the handling in main.c.
..wayne..
Something along these lines might be appropriate. I did a
little more digging as a result of your message here and it
looks like this routine should either be setting up it's own signal
handler or integrate with wait_process and the signal hander
in main(). Repeatedly setting SICHGLD to SIG_IGN is dumb.
--- socket.c 27 Jan 2003 03:35:09 - 1.84
+++ socket.c 24 Jul 2003 19:25:05 -
@@ -374,6 +374,14 @@
}
+static RETSIGTYPE sigchld_handler(int UNUSED(val)) {
+ signal(SIGCHLD, sigchld_handler);
+#ifdef WNOHANG
+ while (waitpid(-1, NULL, WNOHANG) 0) {}
+#endif
+}
+
+
void start_accept_loop(int port, int (*fn)(int, int))
{
int s;
@@ -419,14 +427,7 @@
if (fd == -1) continue;
- signal(SIGCHLD, SIG_IGN);
-
- /* we shouldn't have any children left hanging around
-but I have had reports that on Digital Unix zombies
-are produced, so this ensures that they are reaped */
-#ifdef WNOHANG
-while (waitpid(-1, NULL, WNOHANG) 0);
-#endif
+ signal(SIGCHLD, sigchld_handler);
if ((pid = fork()) == 0) {
int ret;
--
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--
J.W. SchultzPegasystems Technologies
email address: [EMAIL PROTECTED]
Remember Cernan and Schmitt
--
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SIGCHLD SIG_IGN, then wait - warning messages
Rsync maintainers please review rsync bug https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=98740 The code in question is in socket.c in start_accept_loop. The user is getting these warning messages: - Jul 8 12:56:59 ftp kernel: application bug: rsync(1051) has SIGCHLD set to SIG_IGN but calls wait(). Jul 8 12:56:59 ftp kernel: (see the NOTES section of 'man 2 wait'). Workaround activated. - I was able to reproduce that error with rsync server and client on Red Hat OS's on a fairly consistent basis by running an rsync server (rsync version 2.5.6 protocol version 27 from cvs 7/14) from the command line (rsync --daemon), and connecting with an rsync-2.4.6 client with this command: rsync -avv my.server.com::test/one /tmp/rsync_test I also produced the same error by using the same command from an rsync-2.5.6 protocol version 26 client. Here is my /etc/rsyncd.conf file: - log file = /var/log/rsync [test] uid = rsync1 gid = rsync1 path = /rsync_test comment = Rsync Test - Comment - Quoting one of the bug messages, These messages are a warning that rsync is not standards compliant with respect to its handling of child processes. According to POSIX (3.3.1.3) it is unspecified what happens when SIGCHLD is set to SIG_IGN. This code in socket.c: - signal(SIGCHLD, SIG_IGN); /* we shouldn't have any children left hanging around but I have had reports that on Digital Unix zombies are produced, so this ensures that they are reaped */ #ifdef WNOHANG while (waitpid(-1, NULL, WNOHANG) 0); #endif - sets SIGCHLD to SIG_IGN, and *then* waits if WNOHANG is defined. It would appear that if there are still children left to be cleaned up in Digital Unix after setting SIGCHLD to SIG_IGN, that there might be a bug in Digital Unix that rsync is coding a fix for. One coding change could be to change the #ifdef WNOHANG to a #ifdef Digital Unix string, so that only Digital Unix OS's would include and execute the waitpid. This would stop warning messages from being produced. Thanks. -- Hardy Merrill Red Hat, Inc. -- To unsubscribe or change options: http://lists.samba.org/mailman/listinfo/rsync Before posting, read: http://www.catb.org/~esr/faqs/smart-questions.html
