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2DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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21
22DESCRIPTION
23
24 This is a lock coarsening test. There are 2 threads, trying to acquire a shared
25 resource. The 1st thread has a number of adjacent lock that are subject to lock
26 coarsening:
27
28 ...
29
30 synchronized( lock )
31 {
32 lock.foo();
33 }
34
35 // (*)
36
37 synchronized( lock )
38 {
39 lock.foo();
40 }
41
42 ...
43
44
45 The test is written in such a way, that thread 2 will acquire the lock, if and
46 only if thread 1 is somewhere at point (*). Therefore, the fact that lock
47 coarsening occurred is described by the condition (numAcquiredLocks != 0).
48
49IMPLEMENTATION
50 The test has one parameter, -eliminateLocks, that tells whether the JVM option
51 -XX:+EliminateLocks has been specified, so running the test without
52 -eliminateLocks checks that lock coarsening didn't occur, and running it with
53 this option check that lock coarsening occurred.
54
55 Some hacks have been made to force JIT compile the method doit() (see comments in
56 the source).
57
58FAILURE ANALYSIS
59 If test fails try to run it with -XX:+PrintOptoAssembly and -XX:+LogCompilation
60 to understand if this is a test or product bug.
61
62 If compiled code of Thread_1::doit method have lot of locks that surround each
63 lock.foo() then coarsening did not happen and this is a product bug.
64
65 If lock coarsening occurs but not triggered by test then it's a test bug
66 that should be investigated. One of such problems could be caused if method doit()
67 was not compiled due to insufficient warm-up iterations. Also there may be a product bug
68 in compilation.
69