Fix memory leak in Raw.copy(). - #709
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July 12, 2024 19:15
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@jcrist could you please take a look? |
Raw_New borrows a reference to its PyBytesObject argument, so Raw_Copy must still dispose of it. The following is a minimal repro for this issue: import msgspec DECODER = msgspec.msgpack.Decoder(type=msgspec.Raw) PAYLOAD = b"\xda\xff\xff" + (65535 * b"\0") # array of 65535 zeros for _ in range(1000000): raw = DECODER.decode(PAYLOAD) raw.copy()
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Fixes msgspec#1108. `Ext_New` doesn't steal the reference to `data` (it does its own `Py_INCREF`, matching the borrow contract expected by the `Ext` constructor). Both decode branches in `mpack_decode_ext` (typed `Ext` decode, and `Any` decode without an `ext_hook`) passed a fresh reference from `PyBytes_FromStringAndSize` and never released it, leaking one bytes object (the ext payload) per decoded Ext. The `datetime` (code -1) and `ext_hook` branches were not affected. The fix releases the caller's reference after constructing the `Ext`, same pattern as the `Raw.copy()` leak fix (msgspec#709). Verified empirically: RSS delta over 200k decodes of a 1 KiB payload went from ~205 MiB to 0 on both affected branches; the new test fails before the fix (`sys.getrefcount` 3 vs 2) and passes after. Thanks @K-ANOY for the precise report, the ownership analysis there was spot on. Co-authored-by: Siyet <Siyet@users.noreply.github.com>
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Raw_New borrows a reference to its PyBytesObject argument, so Raw_Copy must still dispose of it.
The following is a minimal repro for this issue: