-{section: How to sample the stack with gdb}
+{section: How to sample the stack}
This method is useful when you are called in to diagnose a condor daemon that is using lots of cpu (or blocking a lot on I/O) for an unknown reason. Although crude, I have found this method to lead to the source of trouble in numerous cases.
-Here’s an example gdb script for the schedd:
+If pstack or gstack are available, just use those. If not, you can use gdb.
+
+Here’s an example gdb script for the schedd:
{verbatim}
add-symbol-file /path/to/condor_schedd.dbg
@@ -19,7 +21,7 @@
If the stack shows that the schedd is usually in a certain part of the code, this may lead you to the source of trouble.
-If you need to get the condor admin to do this for you, then it is nice to make it even simpler. Below is a simple script to do the sampling. (Note that it doesn’t load the .dbg file, just to keep things simple.)
+If you need to get the condor admin to do this for you, then it is nice to make it even simpler. Below is a simple script to do the sampling. (Note that it doesn’t load the .dbg file, just to keep things simple.)
{verbatim}
#!/bin/sh
@@ -51,17 +53,17 @@
Callgrind is a wonderful profiling tool. The one big disadvantage of it is that it slows down the application considerably (~20 times in my experience).
-Here’s an example of how to run callgrind on the collector.
+Here’s an example of how to run callgrind on the collector.
{verbatim}
condor_off -collector
# become the user who runs condor
sudo su root
-valgrind —tool=callgrind /path/to/condor_collector -f -p 9618 >& /tmp/callgrind.log < /dev/null &
+valgrind —tool=callgrind /path/to/condor_collector -f -p 9618 >& /tmp/callgrind.log < /dev/null &
PID=$!
{endverbatim}
-You will see some files in the current working directory named “callgrind.out.$PID” and “callgrind.info.$PID”. Change the ownership of these from root to the condor user or callgrind will have trouble writing to them when the program exits.
+You will see some files in the current working directory named “callgrind.out.$PID” and “callgrind.info.$PID”. Change the ownership of these from root to the condor user or callgrind will have trouble writing to them when the program exits.
{verbatim}
chown condor:condor callgrind.*.$PID
