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Diffstat (limited to 'release_docs/RELEASE.txt')
| -rw-r--r-- | release_docs/RELEASE.txt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt index 807d3ab..66b78ac 100644 --- a/release_docs/RELEASE.txt +++ b/release_docs/RELEASE.txt @@ -47,6 +47,31 @@ New Features Configuration: ------------- + - Added an option to make the global thread-safe lock a recursive R/W lock + + Prior to this release, the HDF5 library supported multi-threaded + applications by placing a recursive global lock on the entire library, + thus allowing only one thread into the library at a time. + + While this is still the default, the library can now be built with the + recursive global lock replaced with a recursive read / write (R/W) lock + that allows recursive writer locks. + + Currently, this change results in no functional change in the HDF5 + library, as all threads will have to acquire a write lock on entry, and + thus obtain exclusive access to the HDF5 library as before. However, the + addition of the recursive R/W lock is a prerequisite for further work + directed at allowing some subset of the HDF5 API calls to enter the + library with read locks. + + CMake: HDF5_USE_RECURSIVE_RW_LOCKS (default: OFF, advanced) + + Autotools: --enable-recursive-rw-locks [default=no] + + This feature only works with Pthreads. Win32 threads are not supported. + + (DER - 2021/05/10) + - CMake no longer builds the C++ library by default HDF5_BUILD_CPP_LIB now defaults to OFF, which is in line with the |