On Wed, 8 May 2024 22:40:26 GMT, Serguei Spitsyn <sspit...@openjdk.org> wrote:
>> If the following are all true >> - you are entering is a leaf monitor >> - the current thread has already entered a leaf monitor >> - the rank of the monitor you are entering is lower than the rank of the >> monitor already held >> >> Then you have both a rank order violation and a violation for entering a >> leaf monitor when you have already entered a leaf monitor. My current >> implementation will complain about the rank violation (although can easily >> be made to instead complain about the leaf violation or complain about >> both). Yours will complain about the leaf violation. To make yours instead >> complain about the rank violation, the first loop needs to also check all >> the leaf monitors. Since the 2nd loop also checks all the leaf monitors (but >> for a different reason), this means iterating over the leaf monitors twice. >> Complaining about both violations would also require iterating over the leaf >> monitors twice. > > Okay, thanks. >> Then you have both a rank order violation and a violation for entering a >> leaf monitor when you have already entered a leaf monitor. > > I kind of disagree with the second part of this statement. > My understanding is that the second loop does a little bit different check: > "Violation for entering ANY monitor when you have already entered a leaf > monitor." > Please, note that `rank` can be any rank including those with conditions: > > rank < FIRST_LEAF_DEBUG_RAW_MONITOR > rank >= FIRST_LEAF_DEBUG_RAW_MONITOR > > It seems to me that if the second rule (in my edition) is violated then the > first rule does not matter. > It means that the first rule is for both ranks from the range: > > 0 <= rank < FIRST_LEAF_DEBUG_RAW_MONITOR > ``` Yes, the 2nd loop is a different check. That's why I said it also checks all the leaf monitors "but for a different reason". Your two loops do not flag a rank violation if both monitors are leafs, even if grabbed in the wrong order. It only flags the leaf violation. Your two checks will always catch any violation, it just a matter of whether my example (which is both a leaf and a rank violation) is flagged as a leaf violation or a rank violation (or even both could be indicated if we choose). Yours flags it as a leaf violation. My code flags it as a rank violation. Mine could flag both violations without any additional iterations. Your would need to iterate over the leaf monitors twice to detect if there is both a rank and a leaf violation. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/19044#discussion_r1594784168
