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From "Walsh, Stephen" <>
Subject RE: Unable to start one Cassandra node: OutOfMemoryError
Date Thu, 10 Dec 2015 10:09:47 GMT
8GB is the max recommended for heap size and that’s if you have 32GB or more available.

We use 6GB on our 16GB machines and its very stable

The out of memory could be coming from cassandra reloading compactions_in_progress into memory,
you can check this from the log files if needs be.
You can safely delete this folder inside the data directory.

This can happen if you didn’t stop cassandra with a drain command and wait for the compactions
to finish.
Last time we hit it – was due to testing HA when we forced killed an entire cluster.


From: Jeff Jirsa []
Sent: 10 December 2015 02:49
Subject: Re: Unable to start one Cassandra node: OutOfMemoryError

8G is probably too small for a G1 heap. Raise your heap or try CMS instead.

71% of your heap is collections – may be a weird data model quirk, but try CMS first and
see if that behaves better.

From: Mikhail Strebkov
Reply-To: "<>"
Date: Wednesday, December 9, 2015 at 5:26 PM
To: "<>"
Subject: Unable to start one Cassandra node: OutOfMemoryError

Hi everyone,

While upgrading our 5 machines cluster from DSE version 4.7.1 (Cassandra 2.1.8) to DSE version:
4.8.2 (Cassandra 2.1.11)  one of the nodes can't start with OutOfMemoryError.

We're using HotSpot 64-Bit Server VM/1.8.0_45 and G1 garbage collector with 8 GiB heap.

Average node size is 300 GiB.

I looked at the heap dump with YourKit profiler (<>)
and it was quite hard since it's so big, but can't get much out of it:

As far as I understand the report, there are 1,332,812 instances of org.apache.cassandra.db.Row
which retain 8 GiB. I don't understand why all of them are still strongly reachable?

Please help me to debug this. I don't know even where to start.
I feel very uncomfortable with 1 node running 4.8.2, 1 node down and 3 nodes running 4.7.1
at the same time.


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