[debugserver] Remove unnecessary sleep in MachProcess::AttachForDebug #11773
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…llvm#166674) Remove the unnecessary sleep in MachProcess::AttachForDebug. The preceding comment makes it seem like it's necessary for synchronization, though I don't believe that's the case (see below), and even if it were, sleeping is not a reliable way to achieve that. The reason I don't believe it's necessary is because after we return, we synchronize with the exception thread on a state change. The latter will call and update the process state, which is exactly what we synchronize on. I was able to verify that this is the first time we change the process state: i.e., `GetState` doesn't return a different value before and after the sleep. On top of that, there are 3 more places where we call ptrace attach (`PosixSpawnChildForPTraceDebugging`, `SBLaunchForDebug`, and `BoardServiceLaunchForDebug`) where we don't sleep. rdar://163952037 (cherry picked from commit fa83723)
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Remove the unnecessary sleep in MachProcess::AttachForDebug. The preceding comment makes it seem like it's necessary for synchronization, though I don't believe that's the case (see below), and even if it were, sleeping is not a reliable way to achieve that.
The reason I don't believe it's necessary is because after we return, we synchronize with the exception thread on a state change. The latter will call and update the process state, which is exactly what we synchronize on. I was able to verify that this is the first time we change the process state: i.e.,
GetStatedoesn't return a different value before and after the sleep.On top of that, there are 3 more places where we call ptrace attach (
PosixSpawnChildForPTraceDebugging,SBLaunchForDebug, andBoardServiceLaunchForDebug) where we don't sleep.rdar://163952037
(cherry picked from commit fa83723)