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Fix tsan report in system.stack_trace #9832

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merged 1 commit into from
Mar 24, 2020
Merged

Fix tsan report in system.stack_trace #9832

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10 changes: 5 additions & 5 deletions dbms/src/Storages/System/StorageSystemStackTrace.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ namespace
const pid_t expected_pid = getpid();
const int sig = SIGRTMIN;

int sequence_num = 0; /// For messages sent via pipe.
std::atomic<int> sequence_num = 0; /// For messages sent via pipe.

std::optional<StackTrace> stack_trace;

Expand All @@ -55,7 +55,7 @@ namespace
return;

/// Signal received too late.
if (info->si_value.sival_int != sequence_num)
if (info->si_value.sival_int != sequence_num.load(std::memory_order_relaxed))
return;

/// All these methods are signal-safe.
Expand Down Expand Up @@ -113,7 +113,7 @@ namespace

if (read_res == sizeof(notification_num))
{
if (notification_num == sequence_num)
if (notification_num == sequence_num.load(std::memory_order_relaxed))
return true;
else
continue; /// Drain delayed notifications.
Expand Down Expand Up @@ -178,7 +178,7 @@ void StorageSystemStackTrace::fillData(MutableColumns & res_columns, const Conte
pid_t tid = parse<pid_t>(it->path().filename());

sigval sig_value{};
sig_value.sival_int = sequence_num;
sig_value.sival_int = sequence_num.load(std::memory_order_relaxed);
if (0 != ::sigqueue(tid, sig, sig_value))
{
/// The thread may has been already finished.
Expand Down Expand Up @@ -213,7 +213,7 @@ void StorageSystemStackTrace::fillData(MutableColumns & res_columns, const Conte
res_columns[2]->insertDefault();
}

sequence_num = static_cast<int>(static_cast<unsigned>(sequence_num) + 1);
++sequence_num; /// FYI: For signed Integral types, arithmetic is defined to use two’s complement representation. There are no undefined results.
}
}

Expand Down