I'm getting random regression test fails in parallel mode due to a race
in svn_atomic_namespace__create:
W: ERROR: dump failed: ../src/subversion/libsvn_fs_fs/fs_fs.c:3220:
(apr_err=160052)
W: ERROR: dump failed: svnadmin: E160052: Revprop caching for
'svn-test-work/local_tmp/repos/db' disabled because SHM infrastructure for
revprop caching failed to initialize.
W: ERROR: dump failed: ../src/subversion/libsvn_fs_fs/fs_fs.c:3171:
(apr_err=17)
W: ERROR: dump failed: ../src/subversion/libsvn_subr/named_atomic.c:430:
(apr_err=17)
W: ERROR: dump failed: svnadmin: E000017: Can't get shared memory for named
atomics: File exists
The code does
/* First, look for an existing shared memory object. If it doesn't
* exist, create one.
*/
apr_err = apr_shm_attach(&shared_mem, shm_name, result_pool);
if (apr_err)
{
apr_err = apr_shm_create(&shared_mem,
sizeof(*new_ns->data),
shm_name,
result_pool);
if (apr_err)
return unlock(&new_ns->mutex,
svn_error_wrap_apr(apr_err,
_("Can't get shared memory for named atomics")));
and between the failed attach and the create another process could
create the segment.
I can't see any order in which we can do attach/create that doesn't have
a similar race. I think the best solution is a short loop trying
attach-create a few times before giving up.
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