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Questions tagged [strace]

86 questions
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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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Strace Apache process output showing 24 seconds wait?What can be the reason?

Performed strace on one one of the apache children and its showing 24 seconds between two system calls.How can i determine what is the cause of this behavior.It looks like both children are taking almost same amound of time(24.7 and 23.92)…
ananthan
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DNS lookups eventually become consistently slow in long lived ruby process

I have a Ruby application running on an Ubuntu server, and this application frequently has to make HTTP requests to other services. Some of those services are on an internal domain, some are reachable by public DNS. I have a Consul agent colocated…
Amit Kumar Gupta
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Apache stops communicating with memcache after creating too many vhosts

I've noticed a very peculiar problem with Apache. I have a very high number of virtual hosts set up - it's around 501. Problems started occuring after vhost number 493. First 493 vhosts work as expected, but as soon as I add vhost number 494, PHP…
Jakov Sosic
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MySQL hangs if connection comes from outside the LAN

I have a MySQL Server operating just fine if I access him from his local LAN (192.168.100.0/24). If I try to access hin from another LAN (192.168.113.0/24 in this case) it hangs for a really long time before delivering the result. SHOW PROCESSLIST;…
Subito
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Apache process consumes too much CPU

I have an ubuntu apache/php server running php doing appx 100 hits/sec and a PHP cron running in the background. I get occasionally high CPU load on one of the Apache processes which stays high regardless of traffic or cron activity. It seems to me…
Niro
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trace opening on a certain file

I know how to strace a certain program to see all the files it reads. I know how to see what processes are using a certain file at the moment. But is there a way to log all file opens. I want something like tail -f some/log/file but instead lsof -f…
lard farnwell
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Why is my cron daemon is being killed every few minutes?

As of about a week ago, my cron daemon refuses to stay running. I'm using Debian 6 x64 on an OpenVZ virtual machine. Running something like pgrep cron shows that the daemon isn't running. I start the service with service cron start or…
quietmint
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How do I run strace or ltrace on Tomcat Catalina?

Running ltrace isn't trivial. This RHEL 5.3 system has based on a Tomcat Catalina (servlet container) which uses text scripts to tie everything together. When I tried to find an executable here's the rabbit hole I went down: /etc/init.d/pki-ca9…
flashnode
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Question About No Output From strace

I am using strace to see what certain processes are doing. I have an Apache process that seems to be running forever, taking up 97.8% of a core and almost 2GB of RAM. Now when I run strace on this process there is no output at all. Does this mean…
Josh Pennington
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Centos 6 vs Centos 7 file access performance

I'd like some assistance in trying to figure out what could explain Centos 7 being slower in accessing a file then Centos 6. It's about a 17% difference. Here's a simple test: [root@test-centos6 shm]# time for i in $(seq 0 50000); do stat file >…
Bob
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MySQL reading /etc/hosts.allow and /etc/hosts.deny

The error reporting of one of my services reported problems to connect to my MySQL server. This problems were not consistent, it just happened a few times to different servers. I started debugging using strace and noticed that MySQL is reading both…
boris quiroz
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Apache Timeout / Deadlock When MaxClients Reached

I'm running Apache 2.2, preform MPM, on Debian Squeeze with mod_php (PHP 5.3), listening on several ports (with memcached running on the same machine). Over the past 6 weeks or so, I've been experiencing situations where all Apache connections are…
Will
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strace not showing anything for thread at 100% 'system' CPU

I'm having difficulty with my Python app going to 100% 'system' CPU time across multiple threads for up to 10+ seconds. My (limited) understanding is that 'system' CPU time is time spent in the kernel. strace shows what kernel calls are being made…
Damon Maria
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process works under strace but not normally

I have a process - a perl script - that does: while true check a POP account on a server on the lan process any email found write logs - messages found, actions taken, errors sleep for 15 seconds It's running on a redhat 7.3 server…
Ben Williams
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