[OAK-1639] MarkSweepGarbageCollector improvements

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.20
• Component/s: core
• Assignee: Chetan Mehrotra
• Reporter: Michael Dürig
• Created: 28/Mar/14 13:41
• Updated: 08/Apr/14 12:47
• Resolved: 04/Apr/14 06:15

Description

While reviewing the patch for OAK-1582 I stumbled over a few issues with MarkSweepGarbageCollector that need improving. First an foremost MarkSweepGarbageCollector needs better documentation. The current javadoc as for many methods and arguments their semantics and invariants are unclear.

Furthermore:

• MarkSweepGarbageCollector#init(): why an init method, and not pass the respective arguments directly to the constructor? Also at when are clients allowed to call init? Can I call it while a a GC cycle is currently taking place?

• Is there (do we need) a protection for multiple GCs being initiated in parallel?

• MarkSweepGarbageCollector.Sweeper#run and MarkSweepGarbageCollector.BlobIdRetriever#retrieve catch Exception and e.printStackTrace(). This needs improving.

• MarkSweepGarbageCollector#sweep catches InterruptedExceptionInterruptedException and {{e.printStackTrace()}. This is wrong as at least the threads interrupted status need to be set.

• DocumentNodeStore#getReferencedBlobsIterator is passed into MarkSweepGarbageCollector#init) in DocumentNodeStoreService. Won't this iterator be consumed after the first gc run such that any further run won't do anything?

amitj_76, could you have a look at these points and create sub tasks as required?

Sub-Tasks

• MarkSweepGarbageCollector - Improvements in exception handling and initialization: Closed