2017-12-07 15:50 GMT+01:00 George Joseph <[email protected]>: > > > On Wed, Dec 6, 2017 at 11:13 AM, Olivier <[email protected]> wrote: > >> >> >> 2017-12-06 15:52 GMT+01:00 George Joseph <[email protected]>: >> >>> >>> >>> On Tue, Dec 5, 2017 at 9:20 AM, Olivier <[email protected]> wrote: >>> >>>> Hello, >>>> >>>> I carefully read [1] which details how backtrace files can be produced. >>>> >>>> Maybe this seems natural to some, but how can I go one step futher, and >>>> check that produced XXX-thread1.txt, XXX-brief.txt, ... files are OK ? >>>> >>>> In other words, where can I find an example on how to use one of those >>>> files and check by myself, that if a system ever fails, I won't have to >>>> wait for another failure to provide required data to support teams ? >>>> >>> >>> It's a great question but I could spend a week answering it and not >>> scratch the surface. :) >>> >> >> Thanks very much for trying, anyway ;-) >> >> >>> It's not a straightforward thing unless you know the code in question. >>> The most common is a segmentation fault (segfault or SEGV). >>> >> >> True ! I experienced segfaults lately and I could not configure the >> platform I used then (Debian Jessie) to produce core files in a directory >> Asterisk can write into. >> Now, with Debian Stretch, I can produce core file at will (with a kill -s >> SIGSEGV <processid>). >> I checked ast_coredumped worked OK as it produced thread.txt files and so >> on. >> >> Ideally, I would like to go one step further: check now that a future >> .txt file would be "workable" (and not "you should have compiled with >> option XXX or configured with option YYY) . >> >> >> >>> In that case, the thread1.txt file is the place to start. Since most >>> of the objects passed around are really pointers to objects, the most >>> obvious cause would be a 0x0 for a value. So for instance "chan=0x0". >>> That would be a pointer to a channel object that was not set when it >>> probably should have been. Unfortunately, it's not only 0x0 that could >>> cause a segv. Anytime a program tries to access memory it doesn't own, >>> that signal is raised. So let's say there a 256 byte buffer which the >>> process owns. If there's a bug somewhere that causes the program to try >>> and access bytes beyond the end of the buffer, you MAY get a segv if that >>> process doesn't also own that memory. If this case, the backtrace won't >>> show anything obvious because the pointers all look valid. There probably >>> would be an index variable (i or ix, etc) that may be set to 257 but you'd >>> have to know that the buffer was only 256 bytes to realize that that was >>> the issue. >>> >> >> So, with an artificial kill -s SIGSEGV <processid>, does the bellow >> output prove I have a workable .txt files (having .txt files that let >> people find the root cause of the issue is another story as we probably can >> only hope for the best here) ? >> >> >> # head core-brief.txt >> !@!@!@! brief.txt !@!@!@! >> >> >> Thread 38 (Thread 0x7f2aa5dd0700 (LWP 992)): >> #0 pthread_cond_timedwait@@GLIBC_2.3.2 () at >> ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_timedwait.S:225 >> #1 0x000055cdcb69ae84 in __ast_cond_timedwait (filename=0x55cdcb7d4910 >> "threadpool.c", lineno=1131, func=0x55cdcb7d4ea8 <__PRETTY_FUNCTION__.8978> >> "worker_idle", cond_name=0x55cdcb7d4b7f "&worker->cond", >> mutex_name=0x55cdcb7d4b71 "&worker->lock", cond=0x7f2abc000978, >> t=0x7f2abc0009a8, abstime=0x7f2aa5dcfc30) at lock.c:668 >> #2 0x000055cdcb75d153 in worker_idle (worker=0x7f2abc000970) at >> threadpool.c:1131 >> #3 0x000055cdcb75ce61 in worker_start (arg=0x7f2abc000970) at >> threadpool.c:1022 >> #4 0x000055cdcb769a8c in dummy_start (data=0x7f2abc000a80) at >> utils.c:1238 >> #5 0x00007f2aeddad494 in start_thread (arg=0x7f2aa5dd0700) at >> pthread_create.c:333 >> > > > That's it! The key pieces of information are the function names > (worker_idle, worker_start, etc.), the filename (threadpool.c, etc) and the > line numbers (1131, 1022, etc). > > > > >> >> >>> Deadlocks are even harder to troubleshoot. For that, you need to look >>> at full.txt to see where the threads are stuck and find the 1 thread that's >>> holding the lock that the others are stuck on. >>> >>> Sorry. I wish I had a better answer because it'd help a lot if folks >>> could do more investigation themselves. >>> >>> >>> >>> >>> >>>> >>>> >>>> > -- > _____________________________________________________________________ > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > > Check out the new Asterisk community forum at: https://community.asterisk. > org/ > > New to Asterisk? Start here: > https://wiki.asterisk.org/wiki/display/AST/Getting+Started > > asterisk-users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >
Thank you very much guys, for your replies ! Now, I can't wait our next Segfault to happen ;-))))
-- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- Check out the new Asterisk community forum at: https://community.asterisk.org/ New to Asterisk? Start here: https://wiki.asterisk.org/wiki/display/AST/Getting+Started asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
