Hi Rakesh, First of all, the zookeeper ensemble consists of five Zookeeper servers. Also I have another 10 clients machines used to send write requests to Zookeeper. The benchmark code creates 5 threads (equal to number of Zookeeper server) , each thread associates with one Zookeeper server. So, in this case, each zookeeper server will receive a set of write requests. The benchmark code runs for 30 seconds.
Async tests: * Number of clients In fact, I have different test, each test has different number of clients. For example, the bellow shows the latency corresponds to different number of clients: Five clients: Latency min/avg/max: 235/366/515 Ten clients: Latency min/avg/max: 252/368/505 * Number of threads As explained above, each client creates 5 threads and each thread connects to one Zookeeper server. For instance, test using 5 clients’ machines, each Zookeeper server receives five threads. * data size storing in each znode The data size store in znode is 100 bytes Also, it would be good to monitor : 1) JVM stats(one way is through JMX) like heap, gc activities. This is to see if latency spike corresponds to gc activity or not. If you mean by JVM stats the four word stat command, then the latency result showed above is generated using this command. If you mean something else then I have to read about and tell you late on. 2) Since you are doubting fsync, I think $ iostat would be helpful to see disk statistics. For example, $ iostat -d -x 2 10 and collects the disk latency. Yes, the batch size that I use in SyncrequestProcessor class is 1000 requests. I think this is preferable size. Also, I will try to use iostat. 3) CPU usage through top or sar unix commands. I didn't use sar , but I could see it gives more details like percent of CPU running idle with a process waiting for block I/O etc. Yes, I will use the top command to gathering the resource utilization. However, I don’t think top or sar will answer my question. Because I am thinking there is different between Asynchroned and Synchronized mode for measuring the latency. Thank you for your attention I look forward to hearing from you Ibrahim -----Original Message----- From: Rakesh Radhakrishnan [mailto:[email protected]] Sent: Thursday, October 23, 2014 03:58 م To: [email protected] Subject: Re: Latency in asynchronous mode Hi Ibrahim, In async tests, could you give the details like: * number of clients * number of threads * data size storing in each znode Also, it would be good to monitor : 1) JVM stats(one way is through JMX) like heap, gc activities. This is to see if latency spike corresponds to gc activity or not. 2) Since you are doubting fsync, I think $ iostat would be helpful to see disk statistics. For example, $ iostat -d -x 2 10 and collects the disk latency. 3) CPU usage through top or sar unix commands. I didn't use sar , but I could see it gives more details like percent of CPU running idle with a process waiting for block I/O etc. -Rakesh On Thu, Oct 23, 2014 at 6:44 PM, Alexander Shraer <[email protected]> wrote: > Maybe due to queueing at the leader in asynchronous mode - if in your > experiment you have one client in sync mode the leader has just one op > in the queue at a time On Oct 23, 2014 1:57 PM, "Ibrahim" > <[email protected]> wrote: > > > Hi folks, > > > > I am testing ZooKeeper latency in Asynchronous mode. I am sending > > update > > (write) requests to Zookeeper cluster that consists of 5 physical > > Zookeeper. > > > > So, when I run the stat command I get high latency like: > > Latency min/avg/max: 7/339/392 > > Latency min/avg/max: 1/371/627 > > Latency min/avg/max: 1/371/627 > > Latency min/avg/max: 1/364/674 > > I guess such high latency correspond to fsync (batch requests). But > > I > wish > > if someone could help me and explain this behaviour. > > > > However, testing Zookeeper using Synchronous mode, it gives me > > reasonable result like: > > Latency min/avg/max: 6/24/55 > > Latency min/avg/max: 7/22/61 > > Latency min/avg/max: 7/30/65 > > > > Note that the latency measures in milliseconds. > > > > I look forward to hearing from you. > > > > Ibrahim > > > > > > > > > > > > > > > > -- > > View this message in context: > > > http://zookeeper-user.578899.n2.nabble.com/Latency-in-asynchronous-mod > e-tp7580446.html > > Sent from the zookeeper-user mailing list archive at Nabble.com. > > >
