On 3/28/2015 7:45 AM, Michael Bakonyi wrote: > we were using Solr for about 3 months without problems until a few days ago > it crashed one time and we don't know why. After a restart everything was > fine again but we want to be better prepared the next time this could happen. > So I'd like to know what's the best way to monitor a single Solr-instance and > what logging-configuration you think is useful for this kind of monitoring. > Maybe there's a possibility to automatically restart Solr after it crashed + > to see in detail in the logs what happend right before the crash ..? > > Can you give me any hints? We're using Tomcat 6.X with Solr 4.8.X
Detecting that the instance is down could be done in a lot of ways, including sending an HTTP request and looking for a valid HTTP response code. Do you know why it crashed? Solr normally will not completely crash even when problems are encountered, but there could be a bug, especially in an older release. If it was an OutOfMemoryError exception (which quite often does NOT cause a complete crash), then you can give the java commandline a program/script to run on OOME that can do anything you care to write. A script (bin/oom_solr.sh) is included in the 5.0 download which gets automatically used by the 5.0 startup script on Linux or UNIX systems. That script will completely kill the process. It does not attempt to restart it. Killing the process is safest when an OOME is encountered, because program operation is completely unpredictable when java runs out of memory, and usually Solr will stop working correctly. Thanks, Shawn
