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2200. Data race avoidance for all containers, not only for sequences

Section: 24.2.3 [container.requirements.dataraces] Status: C++14 Submitter: Jonathan Wakely Opened: 2012-10-17 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

24.2.3 [container.requirements.dataraces]/2 says "[…] implementations are required to avoid data races when the contents of the contained object in different elements in the same sequence, excepting vector<bool>, are modified concurrently."

This should say "same container" instead of "same sequence", to avoid the interpretation that it only applies to sequence containers.

[2013-03-15 Issues Teleconference]

Moved to Tentatively Ready.

[2013-04-20 Bristol]

Proposed resolution:

This wording is relative to N3376.

1. Change 24.2.3 [container.requirements.dataraces]/2 as indicated:

   -2- Notwithstanding (16.4.6.10 [res.on.data.races]), implementations are required to avoid data races when the contents of the contained object in different elements in the same sequencecontainer, excepting vector<bool>, are modified concurrently.

   -3- [Note: For a vector<int> x with a size greater than one, x[1] = 5 and *x.begin() = 10 can be executed concurrently without a data race, but x[0] = 5 and *x.begin() = 10 executed concurrently may result in a data race. As an exception to the general rule, for a vector<bool> y, y[0] = true may race with y[1] = true. — end note ]