Searching "Caused by: ..." messages from java stack trace

[henrikg]

Hi,

I'm new to Splunk searches and need help.

We currently have searches to filter out log messages with log level ERROR.
We want to take it one step further and build statistics based on the actual root cause.

The problem is that the root cause is almost always hidden in a long stack trace.

Example stack trace:
Exception in thread "main" java.lang.IllegalStateException: A book has a null property
at com.example.myproject.Author.getBookIds(Author.java:38)
at com.example.myproject.Bootstrap.main(Bootstrap.java:14)
Caused by: java.lang.NullPointerException
at com.example.myproject.Book.getId(Book.java:22)
at com.example.myproject.Author.getBookIds(Author.java:35)
... 1 more

And we are looking for: "java.lang.NullPointerException", and our stack traces can be very long...

Is there some way we can search for it in a good way? Or is there another way to handle this problem?

Thanks.

/ Henrik

[richgalloway · Accepted solution]

Is the entire stack trace in a single event? If so, you may be able to rex to find the root cause.

<your search> | rex "Caused by: (?<rootCause>[\w\.]*)" | ...

[henrikg]

Thanks a lot Rich, it worked perfectly!

I did some modifications since I realised I needed the last root cause (last Caused by: ...).
And I also needed the exception message. So I ended up with this:

rex "Caused by: (?<rootCause>[\w\.].*)(?![\s\S]*Caused by: )"

Not sure if there are any performance implications by doing this, but I will try that out tomorrow.