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| author | Mike Bayer <mike_mp@zzzcomputing.com> | 2020-03-20 11:17:47 -0400 |
|---|---|---|
| committer | Mike Bayer <mike_mp@zzzcomputing.com> | 2020-03-20 11:17:47 -0400 |
| commit | 491333858c46fae8c7f8d0ee6dec1be7c81b83da (patch) | |
| tree | fed418956f9e0030510fa68a949c9bd2b94415d7 | |
| parent | ee9bd719b7fc5f9ad34df8815ccca56d5a7a65cc (diff) | |
| download | sqlalchemy-491333858c46fae8c7f8d0ee6dec1be7c81b83da.tar.gz | |
Correct misleading guidance on multiprocessing
Link the connections intro to the dedicated section
on multiprocessing rather than stating that a separate
engine per process is needed, since this is inaccurate
and vague.
Change-Id: I48c66f88a90db918e864cd198c6aed335e28c7e6
| -rw-r--r-- | doc/build/core/connections.rst | 14 | ||||
| -rw-r--r-- | doc/build/core/pooling.rst | 1 |
2 files changed, 7 insertions, 8 deletions
diff --git a/doc/build/core/connections.rst b/doc/build/core/connections.rst index 5619377de..42806d539 100644 --- a/doc/build/core/connections.rst +++ b/doc/build/core/connections.rst @@ -32,14 +32,12 @@ which represents just one connection resource - the :class:`.Engine` is most efficient when created just once at the module level of an application, not per-object or per-function call. -For a multiple-process application that uses the ``os.fork`` system call, or -for example the Python ``multiprocessing`` module, it's usually required that a -separate :class:`.Engine` be used for each child process. This is because the -:class:`.Engine` maintains a reference to a connection pool that ultimately -references DBAPI connections - these tend to not be portable across process -boundaries. An :class:`.Engine` that is configured not to use pooling (which -is achieved via the usage of :class:`.NullPool`) does not have this -requirement. +.. sidebar:: tip + + When using an :class:`.Engine` with multiple Python processes, such as when + using ``os.fork`` or Python ``multiprocessing``, it's important that the + engine is initialized per process. See :ref:`pooling_multiprocessing` for + details. The engine can be used directly to issue SQL to the database. The most generic way is first procure a connection resource, which you get via the diff --git a/doc/build/core/pooling.rst b/doc/build/core/pooling.rst index ebd396fc5..94064ffc5 100644 --- a/doc/build/core/pooling.rst +++ b/doc/build/core/pooling.rst @@ -430,6 +430,7 @@ Note that the flag only applies to :class:`.QueuePool` use. :ref:`pool_disconnects` +.. _pooling_multiprocessing: Using Connection Pools with Multiprocessing ------------------------------------------- |