how do i find out if JVM is GCing?

On Sun, Jul 12, 2009 at 10:37 PM, Sandeep Tata <sandeep.tata@gmail.com> wrote:
What hardware are you running one?

 dual quadcore intel xeon 2.0 ghz, 32GB ram, and hardware raid config
operating system is fedora core 9


How long does the slowdown last ?

i stopped inserting data after slowdown starts, and it is still slow now after over 10 hours.
however if i stop cassandra and start it, it becomes super fast immediately. till i insert another 100k or so rows when it becomes really slow again.

 

 There are a few reasons for temporary slowdowns ... perhaps the JVM
started GCing?
how do i find out if this is the cause?

 
Cassandra spends time cleaning up the on-disk SSTables
in a process called compaction. This could cause the client to observe
a slowdown.

Things you could try --
Reduce the Memtable size in the config files. (If GCing was the problem)
Increasing the number of SSTables written before compaction kicks in.

can you tell me what numbers i should use?

thanks!