On Wed, Feb 17, 2010 at 4:29 PM, Dan Denton <random.da...@gmail.com> wrote: > On Wed, Feb 17, 2010 at 3:19 PM, Robert Hall <rfh...@berkeley.edu> wrote: >> >> On Feb 17, 2010, at 12:50 PM, Dan Denton wrote: >> >>> On Wed, Feb 17, 2010 at 2:26 PM, Robert Hall <rfh...@berkeley.edu> wrote: >>>> >>>> On Feb 17, 2010, at 12:06 PM, Dan Denton wrote: >>>> >>>>> On Mon, Feb 15, 2010 at 12:53 PM, Robert Hall <rfh...@berkeley.edu> >>>>> wrote: >>>>>> >>>>>> Dan, >>>>>> >>>>>> On Feb 15, 2010, at 10:37 AM, Dan Denton wrote: >>>>>> >>>>>>> Hello all. I’m trying to load test a login page served by tomcat 6, >>>>>>> proxied through apache 2 with mod_proxy. I’m using JMeter 2.3.4 to >>>>>>> conduct the testing. My thread group consists of 500 sessions , and >>>>>>> the sample is a GET of a simple login page. >>>>>>> >>>>>>> JMeter returns errors for a varying percentage of the samples. The >>>>>>> errors returned are generally the following: >>>>>>> >>>>>>> at >>>>>>> >>>>>>> >>>>>>> org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1037) >>>>>>> at >>>>>>> >>>>>>> >>>>>>> org.apache.jmeter.protocol.http.sampler.HTTPSamplerBase.sample(HTTPSamplerBase.java:1023) >>>>>>> at >>>>>>> >>>>>>> >>>>>>> org.apache.jmeter.threads.JMeterThread.process_sampler(JMeterThread.java:346) >>>>>>> at org.apache.jmeter.threads.JMeterThread.run(JMeterThread.java:243) >>>>>>> at java.lang.Thread.run(Unknown Source) >>>>>>> >>>>>>> The issues I’m having are twofold. I’m having difficulty determining >>>>>>> if these errors are coming from JMeter or Tomcat, as they’re displayed >>>>>>> in the response window of JMeter. The developers think the error is >>>>>>> coming from JMeter given the last few lines of the trace above. >>>>>> >>>>>> The developers are correct. >>>>>> >>>>>>> Given that I'm not a programmer I should probably take their word for >>>>>>> it, >>>>>>> but why would JMeter show this error as the response? >>>>>> >>>>>> The system you are running JMeter on isn't able to handle the load. >>>>>> >>>>>>> Second, I've tried tweaking my process counts (startservers, maxspare, >>>>>>> etc...) with no change in the outcome. I can mitigate the issue by >>>>>>> pointing JMeter directly to tomcat, but I need this product to go >>>>>>> through our apache proxy for SSL. >>>>>>> >>>>>>> Any help on this would be greatly appreciated. >>>>>> >>>>>> There must be some JMeter setting that will work otherwise you would be >>>>>> unable >>>>>> to access the webapp over SSL from the system that is hosting JMeter. >>>>>> >>>>>> Try reducing everything to a count of 1 in JMeter. >>>>>> >>>>>> If that doesn't work, there is a problem with the SSL config in JMeter; >>>>>> google "jmeter ssl". >>>>>> >>>>>> Otherwise, try spreading the load our across several JMeter instances >>>>>> installed on separate systems. >>>>>> >>>>>> - Robert >>>>>> >>>>> >>>>> Thanks for the reply Robert. I've set up JMeter 4 slaves, each with at >>>>> least two 2.8 Ghz procs and 2 GB of RAM, and still regardless of >>>>> whether it's 1 node simulating 400 sessions or 4 nodes each simulating >>>>> 100, I still see these errors at 400 sessions or more. Also, when I >>>>> use multiple slaves to execute the test, the percentage of failures >>>>> when simulating 400 sessions is greater and the failures happen >>>>> earlier in the test. >>>>> >>>>> This makes me think that this isn't just an issue with the systems >>>>> running JMeter, but I'm not sure. I've tried tweaking my SSL Session >>>>> Timeout as well, but with no effect. I did this because watching the >>>>> mod_status page on this apache instance, I can see the current session >>>>> count top out at about 330 every time, then subside. My guess was that >>>>> SSL sessions were somehow bottlenecking. >>>>> >>>>> If anyone has any other suggestions, they would be greatly appreciated. >>>>> >>>> >>>> Dan, this sounds like an Apache httpd configuration issue. >>>> >>>> Check the values for the 'KeepAliveTimeout' and 'KeepAlive' directives, >>>> http://httpd.apache.org/docs/2.0/mod/core.html#keepalive >>>> >>>> I suggest using "KeepAlive On" and "KeepAliveTimeout 1"; the latter is >>>> probably defaulted to 15. >>>> >>>> - Robert >>>> >>> Thanks again Robert. My apache proxy has both directives already set, >>> and KeepAliveTimeout was indeed set to 15. I tried running the 400 >>> session test across 4 slaves with KeepAliveTimout set to 1 and 30, and >>> the same result. A failure rate of approximately 20 percent. >>> >>> Are there any other directives you suggest changing? >>> >>> Thanks... >>> >> >> Surprising that KeepAliveTimeout of 1 and 30 produced the same results. >> >> Other directives: (with KeepAliveTimeout of 1) >> >> MaxKeepAliveRequests - defaults to 100, try raising to 500 >> >> Separately, set KeepAlive Off. >> >> Have you looked at the httpd error logs? >> >> - Robert >> --------------------------------------------------------------------- >> The official User-To-User support forum of the Apache HTTP Server Project. >> See <URL:http://httpd.apache.org/userslist.html> for more info. >> To unsubscribe, e-mail: users-unsubscr...@httpd.apache.org >> " from the digest: users-digest-unsubscr...@httpd.apache.org >> For additional commands, e-mail: users-h...@httpd.apache.org >> >> > > Robert, > > With KeepAliveTimout set to 1, and with MaxKeepAliveRequests set to > either 100 or 500, the same results. When using 4 nodes, 100 sessions > a piece, failure rates are between 10 and 30%. With individual nodes > firing off 400 sessions, failure rates are 10% or less. > > With KeepAlive off, the same results. The results are somewhat random, > but around the same failure rates. > > Nothing in the error logs that seems to point to this issue. Only > occasional messages regarding child processes during the restarts for > the configuration changes. > > So far, none of these changes seem to have had an effect. The failure > rates are the same regardless. > > Thanks for the help... >
Robert, Thanks for the reply. There are no firewalls in play here. The original system being tested is a development system (not as robust as our production systems), and the proxy and the tomcat instance serving the webapp were on the same server. I moved the proxy to another machine and that helped push the count to around 500 before we see an error rate around 3%. Based on this, it's very likely this is a case of simple resource limitations on the server. I will be doing more testing next week with hardware more similar to our production systems, which have about 400% more horsepower than our dev systems. Thanks again for your help! --------------------------------------------------------------------- The official User-To-User support forum of the Apache HTTP Server Project. See <URL:http://httpd.apache.org/userslist.html> for more info. To unsubscribe, e-mail: users-unsubscr...@httpd.apache.org " from the digest: users-digest-unsubscr...@httpd.apache.org For additional commands, e-mail: users-h...@httpd.apache.org
