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--- technical:whitepaper:start [2018-12-12 14:50] – frey
+++ technical:whitepaper:start [2022-06-17 12:25] (current) – [rJava: when compilers get too smart] frey
@@ Line 2: / Line 2: @@
 {{ :technical:whitepaper:1344435822_27-edit_text.png?128|}}Some of the content in this area will be in PDF format and may need to be downloaded before being read.
+===== rJava:  When Compilers Get Too Smart =====
+While installing all 16k (nearly 17k) CRAN packages on a recent R 4.1.3 build, many packages with a dependency on rJava would hang when being tested.  [[technical:whitepaper:rJava-gcc-optimization|GDB debugging and analysis of both the C source and runtime assembly code]] revealed an interesting problem with GCC 11.2's compilation of the code.
+===== Open MPI, PSM2, and MPI_Comm_spawn() =====
+The MPI process-spawning API has not been frequently used on our clusters.  A user reported an issue with the Rmpi library and example code that spawns R workers via MPI_Comm_spawn() on the Caviness cluster.  The issue was debugged and addressed for all pertinent versions of Open MPI, and is [[technical:whitepaper:openmpi-psm2-spawn|summarized here]].
+===== Mellanox UCX and Open MPI on DARWIN =====
+During early-access testing of the DARWIN cluster several users reported issues with their MPI jobs' crashing unexpectedly in code locations that worked on previous clusters (like Caviness).  The [[technical:whitepaper:darwin_ucx_openmpi|full troubleshooting and mitigation]] of the issue should be instructive for DARWIN users who attempt to build and manage their own Open MPI libraries on DARWIN.
 ===== /dev/shm exhaustion =====