> It looks like this happens when there is a promotion failure. Java Heap is full. Memory is fragmented. Use C for web scale.
> 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. It's odd to get that out of the box with an 8GB heap on a 1.1.X install. What sort of work load ? Is it under heavy inserts ? Do you have a lot of CF's ? A lot of secondary indexes ? After the messages is it able to reduce heap usage ? Does it seem to correlate to compactions ? Is the node able to get back to a healthy state ? If this is testing are you able to pull back to a workload where the issues doe not appear ? Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 7/07/2012, at 4:33 AM, feedly team wrote: > 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 <aa...@thelastpickle.com> wrote: >> What accounts for the much larger virtual number? some kind of off-heap >> memory? > http://wiki.apache.org/cassandra/FAQ#mmap > >> I'm a little puzzled as to why I would get such long pauses without >> swapping. > 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. > > 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. > > ----------------- > Aaron Morton > Freelance Developer > @aaronmorton > http://www.thelastpickle.com > > 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. >> >> Thanks >> Kireet >> >> On Mon, Jul 2, 2012 at 9:51 PM, feedly team <feedly...@gmail.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 <mb...@terra.com.br> wrote: >> Yeah! Look that. >> http://arstechnica.com/business/2012/07/one-day-later-the-leap-second-v-the-internet-scorecard/ >> I had the same problem. The solution was rebooting. >> >> On Mon, 2 Jul 2012 11:08:57 -0400 >> feedly team <feedly...@gmail.com> wrote: >> >> > Hello, >> > 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. >> >> -- >> Marcus Both >> >> >> > >
