Hi All,
I'd like to ask how to if we can devise advice around an issue I ran into this
week.
One of our test suites processes about 40K files of test fixtures. These inputs
are parsed, processed, and asserted. This randomly fails on a call to
Logger#debug(), randomly in that it happens usually once per build, somewhere
in a logging call. But it usually fails with a call that looks like this:
logger.debug("This is fun" + myFunObject);
To simplify things, let's say that it turns out that after an underlying third
party jar file version upgrade the call to myFunObject#toString() no longer
returns Object#toString() but rather (again to simplify) the contents of the
file that was parsed to create myFunObject. This toString() can be megabytes.
The solution is obvious:
logger.debug("This is fun", myFunObject::toString)
And our CI builds no longer randomly fail since our default logging does not
log at the debug level.
A better solution could be:
logger.debug("This is fun", () -> myFunObject.toString().substring(0, 100))
where I still want _some_ information better than making my own toString() with
System#identityHashCode(Object) or somesuch. Sure, .toString() is still called
but it does not make it down into logging. In my case the OOME happened in
myFunObject::toString so the substring() example would not have worked.
My question is: Should we document some general advice on this pattern and what
should the advice be? Would it make sense to have some features where we
truncate/reject Strings above a threshold. And yes, calling
myFunObject.toString() can still still get me in trouble.
Gary
