Use a ThreadPoolExecutor instead of a ProcessPoolExecutor in dbserver.py because SQLite in macOS is not fork-safe; using the ProcessPoolExecutor a 'ProgrammingError: Cannot operate on a closed database' error is raised. Se also https://bugs.python.org/issue27126
Use a ThreadPoolExecutor instead of a ProcessPoolExecutor in dbserver.py
because SQLite in macOS is not fork-safe; using the ProcessPoolExecutor
a 'ProgrammingError: Cannot operate on a closed database' error is
raised. Se also https://bugs.python.org/issue27126


Former-commit-id: 56ca190cd7605489d325f5a1d839a9624db26d28 [formerly 55da312452ae9359d82d97c49be276e51485ba83] [formerly 55da312452ae9359d82d97c49be276e51485ba83 [formerly 305e0ab5e88e17e2ac658e8b796c4f39aee74fd8]]
Former-commit-id: c21b4ab08e4f7a71ad07b2a90623bd6297fead0b
Former-commit-id: 68b9d8414db25fad44baa2313dcf2cc70d57ece5
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine