RFR: 8280601: ClhsdbThreadContext.java test is triggering codecache related assert in PointerFinder.find() [v2]

[Chris Plummer]

> It's possible for an address to be in the codecache but not in any CodeBlob. Don't assert in this case.
> 
> Also I ran into a couple of other asserts listed below. It looks like since dumping the threadcontext can result in using PointerFinder with fairly random addresses, it is doing a much better job of stress testing PointerFinder than is done by other tests. The root issue in all these asserts is that a random address in the codecache can either be outside of any CodeBlob, or can map to a CodeBlob that is not yet initialized or could even have been freed. PointerFinder and PointerLocation need to be prepared to handled these asserts, and any other exception thrown. 
> 
> sun.jvm.hotspot.utilities.AssertionFailure: found wrong CodeBlob
> at jdk.hotspot.agent/sun.jvm.hotspot.utilities.Assert.that(Assert.java:32)
> at jdk.hotspot.agent/sun.jvm.hotspot.code.CodeCache.findBlobUnsafe(CodeCache.java:140)
> at jdk.hotspot.agent/sun.jvm.hotspot.utilities.PointerFinder.find(PointerFinder.java:138)
> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.JavaThread.printThreadContextOn(JavaThread.java:493)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor$46.doit(CommandProcessor.java:1702)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:2215)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:2185)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.run(CommandProcessor.java:2056)
> at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.run(CLHSDB.java:112)
> at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.main(CLHSDB.java:44)
> at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.runCLHSDB(SALauncher.java:281)
> at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.main(SALauncher.java:500)
> 
> sun.jvm.hotspot.utilities.AssertionFailure: Should have found CodeBlob
> at jdk.hotspot.agent/sun.jvm.hotspot.utilities.Assert.that(Assert.java:32)
> at jdk.hotspot.agent/sun.jvm.hotspot.utilities.PointerFinder.find(PointerFinder.java:140)
> at jdk.hotspot.agent/sun.jvm.hotspot.runtime.JavaThread.printThreadContextOn(JavaThread.java:493)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor$46.doit(CommandProcessor.java:1702)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:2215)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.executeCommand(CommandProcessor.java:2185)
> at jdk.hotspot.agent/sun.jvm.hotspot.CommandProcessor.run(CommandProcessor.java:2056)
> at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.run(CLHSDB.java:112)
> at jdk.hotspot.agent/sun.jvm.hotspot.CLHSDB.main(CLHSDB.java:44)
> at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.runCLHSDB(SALauncher.java:281)
> at jdk.hotspot.agent/sun.jvm.hotspot.SALauncher.main(SALauncher.java:500)

Chris Plummer has updated the pull request incrementally with one additional commit since the last revision:

  Guard against invalid CodeBlobs that may throw exceptions.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7217/files
  - new: https://git.openjdk.java.net/jdk/pull/7217/files/effcc137..44442603

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7217&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7217&range=00-01

  Stats: 20 lines in 2 files changed: 12 ins; 3 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7217.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7217/head:pull/7217

PR: https://git.openjdk.java.net/jdk/pull/7217