thread safety statics work … #1294
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changed static to static const where possible otherwise used std::atomic<> when value is set once then read.
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A new Pull Request was created by @gartung (Patrick Gartung) for CMSSW_7_0_X. thread safety statics work It involves the following packages: L1Trigger/CSCTriggerPrimitives @nclopezo, @mulhearn can you please review it and eventually sign? Thanks. |
| @@ -243,7 +243,7 @@ | |||
| const edm::ParameterSet& ctmb) : | |||
| theEndcap(endcap), theStation(station), theSector(sector), | |||
| theSubsector(subsector), theTrigChamber(chamber) { | |||
| static bool config_dumped = false; | |||
| static std::atomic<bool> config_dumped{false}; | |||
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Looking further in the code, the use of std::atomic<bool> isn't proper since it still allows multiple threads to do the 'initail' work. To make it only one thread one changes
if(... !config_dumped) {
...
config_dumped = true;
}
to
bool expected = false;
if(... config_dumped.compare_exchange_strong(false,true, std::memory_order_acq_rel) ) {
...
}
There is no need for a later config_dumped=true since the compare_exchange_strong will set it to true for the first thread to hit that line.
NOTE: this only works if the body of work in the if(...) { } block doesn't do any work needed by the algorithm after that block. If it does, then we'd have to use std::call_once(...) instead.
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+1 |
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+1 |
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This pull request is fully signed and it will be integrated in one of the next IBs unless changes or unless it breaks tests. @ktf can you please take care of it? |
…mitives Multithreading fixes -- Remove statics in L1Trigger/CSCTriggerPrimitives
changed static to static const where possible otherwise used std::atomic<> when value is changed once