cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Boris Shulman <>
Subject Re: cassandra freezes
Date Thu, 25 Feb 2010 14:49:44 GMT
I don't think it is gc related issue. There is no correlation between
gc times and the freeze times. More over I don't see any gc activity
that lasts for omre than o.03 sec. But there is a correlation between
disk flushing operations. I've noticed that the system freezes each
time when my commit log reaches 1.1G. I have 1024M memtable size so I
assume this is when the data flushing occurs.

On Thu, Feb 25, 2010 at 4:13 PM, Jonathan Ellis <> wrote:
> Then you should check GC timing with -Xverbose:gc option (see:
> for how to modify
> jvm options) for a correlation.
> On Thu, Feb 25, 2010 at 8:09 AM, Boris Shulman <> wrote:
>> In these tests I perform only write operations, no reads.
>> On Thu, Feb 25, 2010 at 4:07 PM, Jonathan Ellis <> wrote:
>>> The only kind of "freeze" that makes sense there is your reads are i/o
>>> bound and the extra disk activity is killing you.  In that case the
>>> fix is to add more RAM, or give less to the JVM so the OS can use more
>>> for buffer cache.
>>> On Thu, Feb 25, 2010 at 8:01 AM, Boris Shulman <> wrote:
>>>> In my case the cassandra node freezes while memtable flush operation
>>>> is performed or compactation operation is performed. How can I
>>>> optimize the cassandra configuration in order to avoid this behavior?
>>>> I've tried both using large memtable size (1G) and small (128M) but in
>>>> every case I have some sort of freezes when the data is flushed to the
>>>> disk.
>>>> Please advice.

View raw message