On 20.05.2014 16:36, Fiedler Roman wrote: > Hello List, > > I'm using strace for quite a while, but today I got a quite unexpected > result. Since this was so confusing, I would be glad about feedback, if the > cause for that could be a) human error in operation of strace, b) > misconception of the principles of syscall tracing, c) some strange > interaction between 32bit kernel/binary on single-core CPU: > > The output: > > # strace -s256 -f /usr/sbin/zabbix_server -c /etc/zabbix/zabbix_server.conf > .... > setgroups32(1, [112]) = 0 > setuid32(109) = 0 > setresgid32(-1, 112, -1) = 0 > setresuid32(-1, 109, -1) = 0 > clone(child_stack=0, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, > child_tidptr=0xb6340768) = 30111 > exit_group(0) = ? > +++ exited with 0 +++ > > > What was unexpected: strace failed to attach to the child. What is special > about the traced process: due to an error, the child process performs just > one open-syscall and exit after clone, the parent process performs an exit > immediately after clone. Due to single-core CPU, it seems more likely, that > the parent continues running after the fork before the child process gets > any chance to do so. > > Question: Is my strace invocation syntax correct and should it capture the > child system calls also? To my understanding, a tracee should be stopped as > soon as strace is attached, also all children are stopped after clone. So > there should be no way to miss any child? > > Kind regards, > Roman > > > PS: I'm using strace version: > ii strace 4.8-1ubuntu5 i386 > A system call tracer >
It seems that the problem you describe has already been filed, discussed and fixed: https://www.mail-archive.com/strace-devel@lists.sourceforge.net/msg03273.html > > > > ------------------------------------------------------------------------------ > "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE > Instantly run your Selenium tests across 300+ browser/OS combos. > Get unparalleled scalability from the best Selenium testing platform available > Simple to use. Nothing to install. Get started now for free." > http://p.sf.net/sfu/SauceLabs > > > > _______________________________________________ > Strace-devel mailing list > Strace-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/strace-devel > ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ Strace-devel mailing list Strace-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/strace-devel
