> Please consider this change which removes the manual transitions to blocked. > This adds a preprocess template/functor which is executed in the destructor > of 'ThreadBlockInVM' if we are going to do any processing. > This gives us a way to backout of the object/raw monitor before suspend or > other processing, such as a safepoint. > > The object monitor code could be straight forward changed to use this instead > of manual transitions. > > Raw monitors on the other hand are a bit more complicated due to 'implicit' > rules (consequences of the specs). > Added a comment in hpp trying to explain it; we cannot simply transition with > a raw monitor held. > This caused the change in the destructor ~ThreadInVMfromNative() (this > specific change have also been tested in unrelated exploration of > transition), now this RAII does the same as we do when going to native from > Java, just setting the state. > Since we are going from an unsafe state, in VM, to a safe state, in native, > we do not need to check the poll. > That made it possible to careful use ThreadInVMfromNative in raw monitors. > > I also remove the early CAS in raw_enter. > We lock a lock to do a CAS, in the uncontended case means CAS on lock then > CAS raw monitor. > Now we instead do a transitions, in the uncontended case means fence, CAS raw > monitor, fence. > (multiple fence (CAS is also a fence) very close to each other have little > additional performance impact on contemporary hardware) > > Passes t1-t7 and manual stressing relevant test groups.
Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision: - Review fixes - Merge branch 'master' into 8265753 - Fixes for Dan - Merge branch 'master' into 8265753 - Removed manual transitions ------------- Changes: - all: https://git.openjdk.java.net/jdk/pull/3875/files - new: https://git.openjdk.java.net/jdk/pull/3875/files/1c6448e3..a8b8469c Webrevs: - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=3875&range=03 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=3875&range=02-03 Stats: 23290 lines in 735 files changed: 8980 ins; 9379 del; 4931 mod Patch: https://git.openjdk.java.net/jdk/pull/3875.diff Fetch: git fetch https://git.openjdk.java.net/jdk pull/3875/head:pull/3875 PR: https://git.openjdk.java.net/jdk/pull/3875
