In my scalability testing I have found you cannot scale out ssh slaves with /dev/random as the entropy source. You need to use /dev/./urandom (JVM bug requires that name btw)
The master on windows is a different story though On Wednesday, 30 July 2014, Mark Waite <[email protected]> wrote: > I thought that a common default on Linux was to block if /dev/random was > to block if the pool of random data was emptied. Refer to > http://en.wikipedia.org/?title=/dev/random for a description. > > I thought that /dev/urandom did not block if the pool of random data was > emptied. That same article describes the differences between the two. > > I've seen cases with some versions of Java and some Linux variants where > Java performance suffered badly when I had emptied the pool of random data. > I think that is why Stephen recommends using /dev/urandom so that your > program won't block while waiting for random data. > > Mark Waite > > > On Tue, Jul 29, 2014 at 10:44 PM, Dean Yu <[email protected] > <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: > >> Obviously, going from 1.509.4 to 1.554.3 is a pretty big jump that >> included lots and lots of changes. However, the fact that the singular act >> of downgrading that library got us back to our prior build times is a big >> smoking gun to me. >> >> > I wonder if something changed upstream... >> >> From the upstream release notes: >> >> >> build217, 2013-06-03: >> >> - Support for SSH agent based authentication. >> >> build216, 2013-03-04: >> >> - Support of unencrypted entries in the known_hosts file. >> - Improved timeout handling. >> >> > BTW you are using /dev/./urandom as an entropy source for the JVM? >> >> Nope. Should we? >> >> -- Dean >> >> >> From: Stephen Connolly <[email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');>> >> Reply-To: "[email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');>" < >> [email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');>> >> Date: Tuesday, July 29, 2014 at 2:16 PM >> To: "[email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');>" < >> [email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');>> >> Subject: Re: SSH slave performance degradation >> >> * KK's changes to window sizes should have *increased* performance >> * My connection bug fixes were surgical IIRC >> * Nicolas's merge of upstream seems to include an EOL change, so hard to >> see what changed there with the Github diff tool: >> https://github.com/jenkinsci/trilead-ssh2/compare/trilead-ssh2-build214-jenkins-3...trilead-ssh2-build217-jenkins-5 >> >> I wonder if something changed upstream... >> >> BTW you are using /dev/./urandom as an entropy source for the JVM? >> >> >> On 29 July 2014 19:51, Dean Yu <[email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: >> >>> Hi folks, >>> We just upgraded our cluster from 1.509.4 to 1.554.3, and discovered a >>> significant increase in our build times. Builds that typically took ~50 to >>> complete started taking ~90 minutes to finish, sometimes spiking to 2 >>> hours. While researching, we found this JIRA[1] which reported that >>> downgrading the trilead-ssh2 jar solved the performance issues. >>> While this ticket talks specifically artifact downloads, we see that >>> our builds as a whole were slower. >>> The trilead-ssh2 dependency version was updated by [2], so it was >>> introduced into 1.536, show would only have made it to LTS with 1.554.1 in >>> April. >>> Looking at the trilead-ssh2 repo[3], it looks like there were a small >>> set of changes: >>> - changes by ndeloof to merge a newer upstream (build214 to build217) >>> - changes by stephenc to fix connection bugs >>> - changes by kohsuke to support package window sizes >>> >>> Anyone have thoughts on the likely culprit? Given the severity of the >>> performance hit we took, I'm surprised that more people haven't reported >>> this. >>> >>> -- Dean >>> >>> [1] https://issues.jenkins-ci.org/browse/JENKINS-20550 >>> [2] >>> https://github.com/jenkinsci/jenkins/commit/bb265c5e95b0fe39128720b903914236962db41b >>> [3] https://github.com/jenkinsci/trilead-ssh2/commits/master >>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "Jenkins Developers" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected] >>> <javascript:_e(%7B%7D,'cvml','jenkinsci-dev%[email protected]');> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Jenkins Developers" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] >> <javascript:_e(%7B%7D,'cvml','jenkinsci-dev%[email protected]');> >> . >> For more options, visit https://groups.google.com/d/optout. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Jenkins Developers" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected] >> <javascript:_e(%7B%7D,'cvml','jenkinsci-dev%[email protected]');> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > > > -- > Thanks! > Mark Waite > > -- > You received this message because you are subscribed to the Google Groups > "Jenkins Developers" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <javascript:_e(%7B%7D,'cvml','jenkinsci-dev%[email protected]');> > . > For more options, visit https://groups.google.com/d/optout. > -- Sent from my phone -- You received this message because you are subscribed to the Google Groups "Jenkins Developers" group. 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