[issue3476] BufferedWriter not thread-safe

[Martin v. Löwis]

Martin v. Löwis <martin at v.loewis.de> added the comment:

I don't think the proposed patch (file11012) makes it thread-safe, and I
believe you cannot get it thread-safe without using thread synchronization.

For example, if two threads simultaneously determine that there is still
space left (len(b) <= free), they might both write to self._write_buf
and self._write_end, and the last writer would win. (In case it isn't
clear how this might happen: thread 1 exhausts its Py_Ticker just after
checking the size, then thread 2 runs a full .write(), then thread 1
continues filling the buffer)

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nosy: +loewis

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue3476>
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