So the reason for the large number of prepared statements is because of the
nature of the application.
One of the periodic job does lookup with a partial key (key prefix, not
filtered queries) for thousands of rows.
Hence the large number of prepared statements.
Almost of the queries once executed are not needed anymore, so its ok for the
older prepared statements to be purged.
All the same, I will do some analysis on the prepared statements table.
Thanks for the tip/pointer!
On 8/22/17, 5:17 PM, "Alain Rastoul" <alf.mmm....@gmail.com> wrote:
On 08/22/2017 05:39 PM, Thakrar, Jayesh wrote:
> Surbhi and Fay,
>
> I agree we have plenty of RAM to spare.
>
Hi
At the very beginning of system.log there is a
INFO [CompactionExecutor:487] 2017-08-21 23:21:01,684
NoSpamLogger.java:91 - Maximum memory usage reached (512.000MiB), cannot
allocate chunk of 1.000MiB
who comes from BufferPool exhaustion (several messages)
From the source&doc
file_cache_size_in_mb
(Default: Smaller of 1/4 heap or 512) Total memory to use for
SSTable-reading buffers.
So here in your configuration it is 512M, may be you should set it to a
higher value in your cassandra.yaml (1/4 => 4G) ?
(also see https://issues.apache.org/jira/browse/CASSANDRA-11681, the
default value may not be accurate)
Another strange thing is the number of prepared statements which also
gives errors: lot of messages like
WARN [ScheduledTasks:1] 2017-08-22 07:09:25,009 QueryProcessor.java:105
- 1 prepared statements discarded in the last minute because cache limit
reached (64 MB)
...
on startup you see:
INFO [main] 2017-08-22 12:50:13,787 QueryProcessor.java:162 - Preloaded
13357 prepared statements
13K different prepared statements sounds a lot...
an issue about that seems to be fixed in 3.11
https://issues.apache.org/jira/browse/CASSANDRA-13641
May be youc should truncate your system.prepared_statements and restart
your node
HTH
--
best,
Alain
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