Hi Aniruddha, Are you using trunk for your tests? On Sep 21, 2012, at 4:42 AM, Aniruddha Laud wrote:
> I'm logging latencies in the per channel bookie client by overriding the > read completion and add completion callbacks. > > When a hedwig subscriber subscribes to a topic and it hasn't consumed any > messages for a long time, it has to issue requests to bookkeeper to read > entries. We are observing very high latencies during these operations. > > throttle limit for the bookkeeper client is set at 5000. We are using the > Hierarchical ledger manager. > We throttle before PerChannelBookieClient, so if the high latency you're observing is in PCBC, then it shouldn't be related to throttling. > The bookies have 5 disks. 1 for the journal, 4 for the ledgers. On the > bookie server pageSize=32768, open file limit = 20000. I checked a few > bookies and the number of open ledgers was around 5000 on each. However, > the add and read latencies on the servers were less than 1 second (measured > using jconsole and the exposed jmx stats). > Did you mean to say 1ms? 1 second for a read/write is a lot. Can you give some more detail about your traffic, like the mix of reads and adds, size of entries, etc.? > Also, the bookie disks are standard spin drives and were doing about 40MBps > reads and 10MBps writes when measured with dstat. Any thoughts would be > helpful. Seems low to me, although I would think that they are not the culprits. -Flavio
