Thanks for reminding me. I filed https://issues.apache.org/jira/browse/HDFS-4911 for this.
4307 was about making the cache robust against programs that change the wall-clock time. best, Colin On Sun, Jun 16, 2013 at 7:29 AM, Harsh J <ha...@cloudera.com> wrote: > Hi Colin, > > Do we have a JIRA already for this? Is it > https://issues.apache.org/jira/browse/HDFS-4307? > > On Mon, Jun 10, 2013 at 11:05 PM, Todd Lipcon <t...@cloudera.com> wrote: >> +1 for dropping the client side expiry down to something like 1-2 seconds. >> I'd rather do that than up the server side, since the server side resource >> (DN threads) is likely to be more contended. >> >> -Todd >> >> On Fri, Jun 7, 2013 at 4:29 PM, Colin McCabe <cmcc...@alumni.cmu.edu> wrote: >> >>> Hi all, >>> >>> HDFS-941 added dfs.datanode.socket.reuse.keepalive. This allows >>> DataXceiver worker threads in the DataNode to linger for a second or >>> two after finishing a request, in case the client wants to send >>> another request. On the client side, HDFS-941 added a SocketCache, so >>> that subsequent client requests could reuse the same socket. Sockets >>> were closed purely by an LRU eviction policy. >>> >>> Later, HDFS-3373 added a minimum expiration time to the SocketCache, >>> and added a thread which periodically closed old sockets. >>> >>> However, the default timeout for SocketCache (which is now called >>> PeerCache) is much longer than the DN would possibly keep the socket >>> open. Specifically, dfs.client.socketcache.expiryMsec defaults to 2 * >>> 60 * 1000 (2 minutes), whereas dfs.datanode.socket.reuse.keepalive >>> defaults to 1000 (1 second). >>> >>> I'm not sure why we have such a big disparity here. It seems like >>> this will inevitably lead to clients trying to use sockets which have >>> gone stale, because the server closes them way before the client >>> expires them. Unless I'm missing something, we should probably either >>> lengthen the keepalive, or shorten the socket cache expiry, or both. >>> >>> thoughts? >>> Colin >>> >> >> >> >> -- >> Todd Lipcon >> Software Engineer, Cloudera > > > > -- > Harsh J
