Use PIPE_NOWAIT on Windows to avoid blocking on writes #781
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compnerd
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Mar 6, 2023
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@swift-ci please test |
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@swift-ci please test Windows platform |
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@swift-ci please test Windows platform |
compnerd
reviewed
Mar 7, 2023
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@swift-ci please test |
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@swift-ci please test Windows platform |
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@swift-ci please test |
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@swift-ci please test Windows platform |
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I ran tests locally. 22/22 passed. |
This was referenced Jan 24, 2025
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libdispatchdepends on non-blocking writes to retry later. For pipes on Windows, we achieved this usingNtQueryInformationFileto get theWriteQuotaAvailablefor the pipe, but this function returns0when there is a blocking read on the receiver side (this appears to be an OS bug), which causes us to never proceed to the write.This change rather sets
PIPE_NOWAITon the pipe's write handle, similar to what is done on other platforms. This call will fail if the pipe handle does not haveFILE_WRITE_ATTRIBUTESset, which is not a problem with the typical case of using aFoundation.Pipe. If we cannot setPIPE_NOWAIT, we will proceed with blocking writes, which in some circumstances could lead to hangs.This resolves an issue with
SourceKit-LSPon Windows where tests and real-life scenarios would hang because a pipe could never be written to.