Lately we have been noticing issues with the Debug Logs.
Missing debug lines
Sometimes either CODE_UNIT_STARTED or CODE_UNIT_FINISHED goes missing. For example The log shows when a trigger finished running but omits its starting point. There are no skipped lines (due to large log size) in between the 2 expected events. We are also seeing debug statements that don't match their sequence in the code. For example if "debug 1" and "debug 2" are written back to back, sometimes we only see "debug 2".
Missing debug logs
Sometimes there are no logs even though the proper window is set for the user.
Nonoperational trace flag overrides
Sometimes overridden trace flags for classes don't work. The Winter '16 release seems to be at fault as explained in this SE post and also in this article.
ENTERING_MANAGED_PKG litter
I know this is a duplicate of my earlier post referenced above but for completeness I'm including it here again. Basically my logs in a namespaced DE org are now filled with ENTERING_MANAGED_PKG statements.
Does anyone have any hacks to offer? Some have suggested that Apex Profiling may be responsible for at least some of the issues but I have it set to None.
I have been developing on SFDC for 7 years now, and I am slowly starting to lose confidence in it. Debugging is the very basic of any development platform and without it you simply can't take it seriously.
ENTERING_MANAGED_PKG
entries bloating the log, be on the lookout forMAXIMUM_DEBUG_LOG_SIZE_REACHED
and "*** Skipped 3799560 bytes of detailed log" messages. Especially the skipped one where it randomly chops out the middle of the log.