[LUCENE-1544] Deadlock: IndexWriter.addIndexes(IndexReader[])

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.4
• Fix Version/s: 2.4.1, 2.9
• Component/s: core/index

Environment

should be ubiquitous... but, Win XP on a MacBookPro (Intel) under Eclipse (Ganymede) using default compiler/runtime

• Lucene Fields: New
• Assignee: Michael McCandless
• Reporter: Doug Sale
• Created: 19/Feb/09 19:21
• Updated: 28/Aug/22 11:57
• Resolved: 22/Feb/09 12:27

Description

A deadlock issue occurs under the following circumstances

• IndexWriter.autoCommit == true
• IndexWriter.directory contains multiple segments
• IndexWriter.AddIndex(IndexReader[]) is invoked

I put together a JUnit test that recreates the deadlock, which I've attached. It is the first test method, 'testAddIndexByIndexReader()'.

In a nutshell, here is what happens:

// 1) AddIndexes(IndexReader[]) acquires the write lock,
// then begins optimization of destination index (this is
// prior to adding any external segments).
//
// 2) Main thread starts a ConcurrentMergeScheduler.MergeThread
// to merge the 2 segments.
//
// 3) Merging thread tries to acquire the read lock at
// IndexWriter.blockAddIndexes(boolean) in
// IndexWriter.StartCommit(), but cannot as...
//
// 4) Main thread still holds the write lock, and is
// waiting for the IndexWriter.runningMerges data structure
// to be devoid of merges with their optimize flag
// set (IndexWriter.optimizeMergesPending()).