Charm++ parallel programming system

[Phil Miller <mille121 AT illinois.edu>]

I've just tagged and pushed a fourth release candidate of Charm++ 6.6 in our repository, v6.6.0-rc4. All outstanding release-critical issues have been closed, so we anticipate that this is the final candidate before the release. Please test and benchmark the code with your applications, and let us know urgently if any issues become apparent.

git clone -b v6.6.0-rc4 http://charm.cs.illinois.edu/gerrit/charm charm-6.6

Since the previous release candidate, v6.6.0-rc3, we have made a number of bug fixes and other improvements in the codebase. The most salient differences are as follows:

- SMP builds on LRTS-based machine layers (pamilrts, gni, mpi, netlrts, verbs) support tracing messages through communication threads

- Fix a performance bug in SMP builds where PEs would prefer work from the node-level queue over their own private queue

- Thread affinity mapping with +pemap now supports Intel's Hyperthreading more conveniently

- After restarting from a checkpoint, thread affinity will use new +pemap/+commap arguments

- CkIO parallel output library is now more robust and works with checkpoint/restart

- CkLoop can now be used with Charm++'s intrinsic checkpoint/restart functionality

- SMP builds: Fix enough data races, especially during startup, so that ThreadSanitizer output is useful for application-level debugging

- net and verbs: prevent a rare deadlock resulting from inadvertent recursive lock acquisition

- Cray XC30: Fix SMSG corruption that caused mysterious crashes and hangs (#401, #486, #533)

- Blue Gene Q: Set options to avoid miscompilation under certain XL compiler versions (#481)

A detailed enumeration of major changes in this release relative to 6.5 can be found in our issue tracker:
https://charm.cs.illinois.edu/redmine/projects/charm/issues?f[]=fixed_version_id&group_by=tracker&op[fixed_version_id]=%3D&set_filter=1&sort=id&utf8=%E2%9C%93&v[fixed_version_id][]=4

and a more detailed list can be seen in the commit logs of the repository, mentioned above.