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Questions tagged [strace]

84 questions
31
votes
3 answers

How to set strace output characters string width to be longer?

Strangely i can't find it any where but when i stdout the output of strace into afile like this: strace foo.exe | & tee foo.log the out put is to short, how can i make the width longer?
user61104
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6 answers

Find out what high CPU usage apache process is actually doing?

Currently having a few issues with our server where, intermittently, we seem to get apache processes which just run and run, taking up 100% CPU. When running top, we see the following: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ …
BT643
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13
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1 answer

Can strace show me the filename/path for read/write syscalls

If, on Linux, I strace a process, then the reads and writes are shown with the file descriptor handle number. If I look in /proc/$PID/fd I can see the symlinks to the files that correspond to the fd number (if applicable). Is there anyway to get…
Amandasaurus
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13
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4 answers

Monitor all newly spawned processes on a Linux machine

Sometimes a process comes and goes faster than I can ps aux, I tried watch -d -n0.1 "ps aux | tail" but again, that's restricted to 1/10th of a second. What I really want is to run a command and follow all new processes, one per line, as they spawn.…
Vasiliy Sharapov
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10
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4 answers

How would you simplify this command?

I'm quite new to strace / netstat / etc. I'm using this command to get a trace of the apache process handling my request (telnet), is there a way to simplify it a bit? sudo strace -o /tmp/strace -f -s4096 -r -p $(netstat -antlp | \ grep $(lsof…
Andrei Serdeliuc
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9
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5 answers

"yum clean" hangs - what to try next?

I run a number of CentOS servers. I was recently doing the occasional yum update but this failed on a handful of the servers. On most I have been able to move forward by doing: # yum clean all # rm -f /var/lib/rpm/__db* # rpm --rebuilddb # yum…
Hamish Downer
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9
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3 answers

Monitor system CPU / system calls in Linux

I have a couple processes that are eating up a lot of system CPU time (as determined by looking at vmstat). Is there an easy way to find out what kind of system calls are being made? I know there is strace, but is there a quicker and easier way? …
bajafresh4life
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8
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2 answers

tail -f not following log file in Docker container

I am seeing some strange behavior running the tail -f command inside a Docker container in CoreOS. There are a number of variables I can think of that may be contributing to the problem but I am not sure what I need to do to troubleshoot first. On…
jmreicha
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6
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1 answer

strace shows long time reading from mysql socket - mysql takes long time to execute query?

My Apache server takes long time to process request. I attached strace to it and can see the two following delays: 1) Very critical (143 seconds to process) 1335 0.000037 write(16, "\235\0\0\0\3INSERT INTO `br_anonymous_user_tokens`…
Max Koretskyi
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6
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1 answer

Java process (OpenDS) consumes all cpu (futex flood) - how to debug futex?

Today I noticed that my LDAP server (OpenDS) consumes 100% CPU on every available core. Fast diagnose showed me that there is a lot of ETIMEDOUT during the futex lock. How Can I debug it to figure out what is happening and how to fix…
bluszcz
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5
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1 answer

Strace poll, trying to diagnose bottleneck

I have no strace skill and knowlegde, but im trying to work through a problem where my clients application is awfully slow. And im trying to find out where the bottleneck / problem may lie. So I ran /etc/init.d/apache2 stop && strace -Tf -o…
Brent
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4
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1 answer

debugging irssi using 100% cpu

I have a debian VM I'm running on an ESX4.0 server. This VM hosts a number of users, each running an irssi session inside a screen instance. This is working quite well, except for one user. For some reason, this irssi session keeps peaking at 100%…
zigdon
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4
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0 answers

mysql client slow login strace

I am experiencing an issue with slow connections/logins to a loaded mysql server, even when connecting via the unix socket file (CentOS 6.3). Queries are completing very quickly -- (0.00 sec) in this case -- but the login takes up to several…
carillonator
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4
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2 answers

How to resolve high CPU + excessive stat("/etc/localtime") and clock_gettime(CLOCK_REALTIME) calls

I've been experiencing really high CPU on a ruby on rails app (see stack below) and have been trying to diagnose the possible causes to no avail. Stack: ruby 1.9.3 rails 3.2.6 Apache/2.2.21 (Debian) Phusion Passenger 3.0.11 Whenever I run strace…
Yemster
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1 answer

Why does strace open, read 512 bytes, and THEN fstat libncurses?

I've got the following strace output that I'm going through to teach myself a little more about the flow of programs. Here's the section that's confusing me: 16:08:02 open("/lib/libncurses.so.5", O_RDONLY) = 3 <0.000046> 16:08:02 read(3, "\x7f\"...,…
MLACitation
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