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Don't drop all traces if frequency is too high

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This commit is contained in:
Alexey Milovidov 2019-07-24 22:03:26 +03:00
parent 796dfeb44e
commit f031d064b6
1 changed files with 7 additions and 1 deletions
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8
dbms/src/Common/QueryProfiler.cpp
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@ -47,11 +47,17 @@ namespace
/// Thus upper bound on query_id length should be introduced to avoid buffer overflow in signal handler.
constexpr size_t QUERY_ID_MAX_LEN = 1024;
thread_local size_t write_trace_iteration = 0;
void writeTraceInfo(TimerType timer_type, int /* sig */, siginfo_t * info, void * context)
{
/// Quickly drop if signal handler is called too frequently.
/// Otherwise we may end up infinitelly processing signals instead of doing any useful work.
if (info && info->si_overrun > 0)
++write_trace_iteration;
if (info
&& info->si_overrun > 0
/// But pass with some frequency to avoid drop of all traces.
&& write_trace_iteration % info->si_overrun != 0)
return;
constexpr size_t buf_size = sizeof(char) + // TraceCollector stop flag