It looks like this happens when there is a promotion failure.
Also is it normal to see the "Heap is xx full. You may need to reduce memtable and/or cache sizes" message quite often? I haven't turned on row caches or changed any default memtable size settings so I am wondering why the old gen fills up.
I reduced the load and the problem hasn't been happening as much. After enabling gc logging, I see messages mentioning promotion failed when the pauses happen. It looks like this happens when there is a promotion failure. From reading on the web it looks like I could try reducing the CMSInitiatingOccupancyFraction value and/or decreasing the young gen size to try to avoid this scenario.Also is it normal to see the "Heap is xx full. You may need to reduce memtable and/or cache sizes" message quite often? I haven't turned on row caches or changed any default memtable size settings so I am wondering why the old gen fills up.
On Wed, Jul 4, 2012 at 6:28 AM, aaron morton <firstname.lastname@example.org> wrote:http://wiki.apache.org/cassandra/FAQ#mmapWhat accounts for the much larger virtual number? some kind of off-heap memory?The two are not related. On startup the JVM memory is locked so it will not swap, from then on memory management is pretty much up the JVM.I'm a little puzzled as to why I would get such long pauses without swapping.Getting a lot of ParNew activity does not mean the JVM is low on memory, it means there is a lot of activity in the new heap.If you have a lot of insert activity (typically in a load test) you can generate a lot of GC activity. Try reducing the load to a point where it does not ht GC and then increase to find the cause. Also if you can connect JConole to the JVM you may get a better view of the heap usage.Hope that helps.On 3/07/2012, at 3:41 PM, feedly team wrote:Couple more details. I confirmed that swap space is not being used (free -m shows 0 swap) and cassandra.log has a message like "JNA mlockall successful". top shows the process having 9g in resident memory but 21.6g in virtual...What accounts for the much larger virtual number? some kind of off-heap memory?I'm a little puzzled as to why I would get such long pauses without swapping. I uncommented all the gc logging options in cassandra-env.sh to try to see what is going on when the node freezes.
ThanksKireetOn Mon, Jul 2, 2012 at 9:51 PM, feedly team <email@example.com> wrote:
Yeah I noticed the leap second problem and ran the suggested fix, but I have been facing these problems before Saturday and still see the occasional failures after running the fix.Thanks.On Mon, Jul 2, 2012 at 11:17 AM, Marcus Both <firstname.lastname@example.org> wrote:Yeah! Look that.
I had the same problem. The solution was rebooting.
On Mon, 2 Jul 2012 11:08:57 -0400
feedly team <email@example.com> wrote:
> I recently set up a 2 node cassandra cluster on dedicated hardware. In
> the logs there have been a lot of "InetAddress xxx is now dead' or UP
> messages. Comparing the log messages between the 2 nodes, they seem to
> coincide with extremely long ParNew collections. I have seem some of up to
> 50 seconds. The installation is pretty vanilla, I didn't change any
> settings and the machines don't seem particularly busy - cassandra is the
> only thing running on the machine with an 8GB heap. The machine has 64GB of
> RAM and CPU/IO usage looks pretty light. I do see a lot of 'Heap is xxx
> full. You may need to reduce memtable and/or cache sizes' messages. Would
> this help with the long ParNew collections? That message seems to be
> triggered on a full collection.