That is what I was also thinking about, thanks for jumping in Todd. I was simply not sure if that is just on .27 or all after that one and the defaults have never been increased.
On Wed, Nov 17, 2010 at 8:24 PM, Todd Lipcon <t...@cloudera.com> wrote: > On that new of a kernel you'll also need to increase your epoll limit. Some > tips about that here: > > http://www.cloudera.com/blog/2009/03/configuration-parameters-what-can-you-just-ignore/ > > Thanks > -Todd > > On Wed, Nov 17, 2010 at 9:10 AM, Lars George <lars.geo...@gmail.com> wrote: > >> Are you running on EC2? Couldn't you simply up the heap size for the >> java processes? >> >> I do not think there is a hard and fast rule to how many xcievers you >> need, trial and error is common. Or ifmyou have enough heap simply set >> it too high, like 4096 and that usually works fine. It all depends on >> how many regions and column families you have on each server. >> >> Lars >> >> On Wed, Nov 17, 2010 at 5:31 PM, Lucas Nazário dos Santos >> <nazario.lu...@gmail.com> wrote: >> > I'm using Linux, the Amazon beta version that they recently released. I'm >> > not very familiar with Linux, so I think the kernel version >> > is 2.6.34.7-56.40.amzn1.x86_64. Hadoop version is 0.20.2 and HBase >> version >> > is 0.20.6. Hadoop and HBase have 2 GB each and they are not sawpping. >> > >> > Besides all other questions I posed, I have one more. How can I calculate >> > the maximum number of xcievers? Is there a formula? >> > >> > Lucas >> > >> > >> > >> > On Wed, Nov 17, 2010 at 2:12 PM, Lars George <lars.geo...@gmail.com> >> wrote: >> > >> >> Hi Lucas, >> >> >> >> What OS are you on? What kernel version? What is your Hadoop and HBase >> >> version? How much heap do you assign to each Java process? >> >> >> >> Lars >> >> >> >> On Wed, Nov 17, 2010 at 3:05 PM, Lucas Nazário dos Santos >> >> <nazario.lu...@gmail.com> wrote: >> >> > Hi, >> >> > >> >> > This problem is widely know, but I'm not able to come up with a decent >> >> > solution for it. >> >> > >> >> > I'm scanning 1.000.000+ rows from one table in order to index their >> >> content. >> >> > Each row has around 100 KB. The problem is that I keep getting the >> >> > exception: >> >> > >> >> > Exception in thread >> >> "org.apache.hadoop.dfs.datanode$dataxceiveser...@82d37" >> >> > java.lang.OutOfMemoryError: unable to create new native thread >> >> > >> >> > This is a Hadoop exception and it causes the DataNote to go down, so I >> >> > decreased the dfs.datanode.max.xcievers from 4048 to 512. Well, that >> led >> >> me >> >> > to another problem: >> >> > >> >> > java.io.IOException: xceiverCount 513 exceeds the limit of concurrent >> >> > xcievers 512 >> >> > >> >> > This time the DataNode doesn't die, nor HBase, but my scan, and the >> whole >> >> > indexing process, suffers a lot. >> >> > >> >> > After reading different posts about this issue, I have the impression >> >> that >> >> > HBase can't handle this limits transparently for the user. The scanner >> is >> >> a >> >> > sequential process, so I thought it would free Hadoop resources >> already >> >> used >> >> > in order to make room for new requests for data under HDFS. What I am >> >> > missing? Should I slow down the scanning process? Should I scan >> portions >> >> of >> >> > the table sequentially instead of doing a full scan in all 1.000.000+ >> >> rows? >> >> > Is there a timeout so unused Hadoop resources can be released? >> >> > >> >> > Thanks in advance, >> >> > Lucas >> >> > >> >> >> > >> > > > > -- > Todd Lipcon > Software Engineer, Cloudera >
