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Questions tagged [strace]

86 questions
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High httpd CPU usage, server load, strace is stuck

I'm runnning Directadmin with apache2 and MariaDB server. But I'm having a hard time to understand why my server's CPU usage is so high. htop screenshot When I try to look what is happening with strace, for some reason it is stuck on…
N. G.
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Stack trace of mount command shows File not found error

When I run a program, I am getting a mount error: [root@host ~]# ip vrf exec wan1 /usr/sbin/ssh root@1.2.3.4 Failed to mount cgroup2: No such file or directory I know my kernel supports cgroup2: [root@host network-scripts]# cat /proc/filesystems…
Sam Alsalem
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Select waiting on what?

I have a python 2.7 app running on RHEL 6 that occasionally hangs. If I strace the app, I get this repeatedly: [pid 180442] select(0, NULL, NULL, NULL, {10, 0}) = 0 (Timeout) [pid 180442] select(0, NULL, NULL, NULL, {10, 0}) = 0 (Timeout) What is…
user171971
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Debugging slow wordpress site with strace

I'm trying to get to the bottom of a wordpress site that runs very slowly: on requesting a page, it hangs for around 20 seconds before the page starts to load. I've tried the usual things: WP debug mode, checking for slow MySQL queries, disabling…
Ian480
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Apache strace getsockname call is slow

While load testing I am getting almost 100% CPU usage by Apache processes. To find out the root cause I attached Apache process with strace and found slow calls. 11840 0.000063 accept4(3, {sa_family=AF_INET, sin_port=htons(34640),…
Bob Meliev
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Intentionally stop a process from responding

Is there any way to intentionally prevent a process from responding - ie. not close or kill it, but stop it dead in it's track, so it immediately stops processing anything? I've often found myself wanting to force a process into a non-responsive…
Mikk3lRo
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Linux high iowait without block device activity

I'm having a hard time figure out the reason cause high iowait on my server. top: %Cpu(s): : 30.0 us, 5.4 sy, 0.0 ni, 53.9 id, 10.1 wa, 0.0 hi, 0.7 si, 0.0 st iostat: Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz…
forke
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SystemTap - filter own syscalls (system-wide trace)

I want to write simple strace-like script using SystemTap. Main goal is to catch only some system calls (like open, close, read, write etc.) for all processes in system. (Can't do that with strace because strace'ing whole system is equal to instant…
KaP
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upstart - supervisord fork count > 2 (can;t get supervisord to start on boot)

i'm trying to use upstart so that supervisord starts automatically at boot. my supervisord is in a virtual environment. I've configured it to run in foreground mode with -n param and it works if started manually but refuses to start on…
w-01
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How to watch a file, who accesses or uses

I am looking forward a way to watch a file to get following information Which process does open, read, write it? When? Result. (e.g. can they write on it, or can they read it, etc.) Strace helps us to watch which files a process opens, but how can…
Shnkc
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MySQL sandbox strace option

Latest MySQL Sandbox version uses environment variable SBDEBUG to start mysql instances in debug mode, but i can't pass mysql --debug option. export SBDEBUG=d:t:O,/tmp/client.trace cd ~/sandboxes/msb_5_6_13 ./start I want to get strace output. How…
artyomboyko
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Troubleshooting SUDO Slowness with STRACE

I'm having trouble with sudo on some systems. It is taking anywhere from 15-30 seconds to complete a sudo command or to even login to the system. I ran an strace and can see where the delay is happening, but I'm not sure what's wrong. It seems…
Matt Mencel
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strace vs. log4cxx performance hit?

I need to debug some issue on a production server, and I'm trying to decide whether to use strace or the log4cxx logging library; one crucial characteristic I need to know before, is which of the two would have lower impact on performance (speed,…
akavel
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Trying to diagnose bottleneck for apache

I am trying to diagnose bottleneck for a apache(v 2.0.52) server using strace. It looks like call to poll is slowing the process. Below is one example poll([{fd=10, events=POLLIN}], 1, 120000) = 0 <119.996719> ls -l /proc/pid/fd returns 10 ->…
Vajra
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Interfacing strace with Process Name instead of PID

How do I implement a wrapper script pstrace in bash that changees the interface of [sudo] strace -c -p [PID] to [sudo] pstrace -c -p [PROCESS-NAME] similar to how killall [PROCESS-NAME] is used. With completion and everything.
Nordlöw
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