Re: [Bigdata-developers] After a timeout I get only timeouts

[Brad B. <be...@bl...>]

Daniel,

On other option to try is varying the queryThreadPoolSize in the web.xml
parameters.

Thanks, --Brad

<context-param>

   <description>The size of the thread pool used to service SPARQL queries
-OR-

    ZERO (0) for an unbounded thread pool.</description>

   <param-name>queryThreadPoolSize</param-name>

   <param-value>16</param-value>

  </context-param>

On Wed, Apr 20, 2016 at 3:30 PM, Daniel Hernandez <da...@de...> wrote:

> Hi,
>
> I have run the experiments again, but now using different parameters in
> the request:
>
> 1. With no options.
> 2. With the option timeout=1.
> 3. With the options timeout=1 and analytic=true.
>
> Simultaneously, I set a timeout in the HTTP client of 120 seconds. Then
> I run the 500 queries. In the three cases queries have small time
> responses,
> but when some of them get a timeout then, all the following get a timeout.
> In the case 1 the first timeout was produced in the query 37, in the second
> in the query 39 and in the third in the query 41. It seems, that the
> timeout
> was not produced because these queries where specially difficult but
> because a process that is initiated a while after starting running the
> queries.
> I guess that this process is the garbage collector.
>
> What can I do to avoid this issue and to improve the resource usage of the
> machine?
>
> Cheers,
> Daniel
>
>  ---- On mié, 20 abr 2016 11:30:23 -0300 Daniel Henández <da...@de...>
> wrote ----
>  > Hi,
>  >
>  > I, running an experiment with 583 millions of triples loaded into
>  > Blazegraph 2.1.0. I have 500 queries generated randomly with similar
>  > complexity. I started running these queries with a timeout of 120
>  > seconds in the http client. The first queries get small times around 2
>  > seconds, except some that gets around 40 seconds. However, in query 37 I
>  > got a timeout. Then, all the following queries get timeouts.
>  >
>  > I guessed that this behavior was because the server was working in the
>  > previous query when the following queries arrive. That is, the server
>  > does not notice that the client have a timeout, so it is not waiting for
>  > a result.
>  >
>  > I found the timeout option in the documentation. Thus, now I'm running
>  > queries with the option &timeout=1 to check if this behavior was because
>  > running queries simultaneously. I starting getting only results in less
>  > than 1 second, and some trunked results with an internal timeout error
>  > message that truncate the JSON output. However, after some queries I get
>  > the timeout in the client again, and then all the following queries get
>  > timeout.
>  >
>  > Now I guess that a GC job that avoid receiving more queries by the
>  > server. I set the parameter -Xmx6g in the java command. The machine have
>  > 32GB of RAM and 6 cores. I do not put more memory in the heap, because
>  > the documentation does not recommend it. However, top says that the
>  > process has VIRT=6913m RES=781m and CPU=104%. That is, the process is
>  > underusing the machine resources.
>  >
>  > I found that I can use the option analytic to using the system heap
>  > instead of the java heap. The documentation said that this will solve
>  > the GC issue.
>  >
>  > Do you think that am I right in suppositions about the GC?
>  >
>  > Cheers,
>  > Daniel
>  >
>  >
>  >
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