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*: fix data race occurred in SharedQueryBlockInputStream. #5309

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*: fix data race occurred in SharedQueryBlockInputStream. #5309

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be8cb5e
update
ywqzzy Jul 7, 2022
b41ab38
refine.
ywqzzy Jul 8, 2022
4ef9b2b
fix clang tidy.
ywqzzy Jul 8, 2022
58fefca
refine with RAII.
ywqzzy Jul 8, 2022
2ded91c
remove some dead code.
ywqzzy Jul 8, 2022
2cb0daa
add more locks.
ywqzzy Jul 11, 2022
4112f7e
Merge branch 'master' of https://github.com/pingcap/tiflash into fix_…
ywqzzy Jul 11, 2022
5d5036d
fix build.
ywqzzy Jul 11, 2022
b57c117
refine
ywqzzy Jul 12, 2022
75ac68b
address comments
ywqzzy Jul 14, 2022
d013459
format.
ywqzzy Jul 14, 2022
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237 changes: 128 additions & 109 deletions dbms/src/DataStreams/IProfilingBlockInputStream.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,24 +12,23 @@
// See the License for the specific language governing permissions and
// limitations under the License.

#include <Interpreters/Quota.h>
#include <Interpreters/ProcessList.h>
#include <DataStreams/IProfilingBlockInputStream.h>

#include <Interpreters/ProcessList.h>
#include <Interpreters/Quota.h>

namespace DB
{

namespace ErrorCodes
{
extern const int TOO_MANY_ROWS;
extern const int TOO_MANY_BYTES;
extern const int TOO_MANY_ROWS_OR_BYTES;
extern const int TIMEOUT_EXCEEDED;
extern const int TOO_SLOW;
extern const int LOGICAL_ERROR;
extern const int BLOCKS_HAVE_DIFFERENT_STRUCTURE;
}
extern const int TOO_MANY_ROWS;
extern const int TOO_MANY_BYTES;
extern const int TOO_MANY_ROWS_OR_BYTES;
extern const int TIMEOUT_EXCEEDED;
extern const int TOO_SLOW;
extern const int LOGICAL_ERROR;
extern const int BLOCKS_HAVE_DIFFERENT_STRUCTURE;
} // namespace ErrorCodes


IProfilingBlockInputStream::IProfilingBlockInputStream()
Expand All @@ -51,21 +50,25 @@ Block IProfilingBlockInputStream::read(FilterPtr & res_filter, bool return_filte
total_rows_approx = 0;
}

if (!info.started)
{
info.total_stopwatch.start();
info.started = true;
}

UInt64 start_time;
Block res;
{
auto lock = get_lock();
if (!info.started)
{
info.total_stopwatch.start();
info.started = true;
}

if (isCancelledOrThrowIfKilled())
return res;

auto start_time = info.total_stopwatch.elapsed();
if (isCancelledOrThrowIfKilled())
{
return res;
}
start_time = info.total_stopwatch.elapsed();

if (!checkTimeLimit())
limit_exceeded_need_break = true;
if (!checkTimeLimit())
limit_exceeded_need_break = true;
}

if (!limit_exceeded_need_break)
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limit_exceeded_need_break is still not in lock protection.

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I have protected it, but IMO the code is hard to read.

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@gengliqi gengliqi Jul 14, 2022 •
edited
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Hmmm...I see that limit_exceeded_need_break is not an atomic variable and is read without a lock. You can see https://stackoverflow.com/questions/14624776/can-a-bool-read-write-operation-be-not-atomic-on-x86 for more information.

{
Expand All @@ -77,16 +80,19 @@ Block IProfilingBlockInputStream::read(FilterPtr & res_filter, bool return_filte

if (res)
{
info.update(res);
{
auto lock = get_lock();
info.update(res);

if (enabled_extremes)
updateExtremes(res);
if (enabled_extremes)
updateExtremes(res);

if (limits.mode == LIMITS_CURRENT && !limits.size_limits.check(info.rows, info.bytes, "result", ErrorCodes::TOO_MANY_ROWS_OR_BYTES))
limit_exceeded_need_break = true;
if (limits.mode == LIMITS_CURRENT && !limits.size_limits.check(info.rows, info.bytes, "result", ErrorCodes::TOO_MANY_ROWS_OR_BYTES))
limit_exceeded_need_break = true;

if (quota != nullptr)
checkQuota(res);
if (quota != nullptr)
checkQuota(res);
}
}
else
{
Expand All @@ -110,36 +116,52 @@ Block IProfilingBlockInputStream::read(FilterPtr & res_filter, bool return_filte
}
#endif

info.updateExecutionTime(info.total_stopwatch.elapsed() - start_time);
{
auto lock = get_lock();
info.updateExecutionTime(info.total_stopwatch.elapsed() - start_time);
}
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In progressImpl function, info still may be used without lock protection.

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ditto

return res;
}


void IProfilingBlockInputStream::readPrefix()
{
auto start_time = info.total_stopwatch.elapsed();
UInt64 start_time;
{
auto lock = get_lock();
start_time = info.total_stopwatch.elapsed();
}
readPrefixImpl();

forEachChild([&] (IBlockInputStream & child)
{
forEachChild([&](IBlockInputStream & child) {
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child.readPrefix();
return false;
});
info.updateExecutionTime(info.total_stopwatch.elapsed() - start_time);
{
auto lock = get_lock();
info.updateExecutionTime(info.total_stopwatch.elapsed() - start_time);
}
}


void IProfilingBlockInputStream::readSuffix()
{
auto start_time = info.total_stopwatch.elapsed();
forEachChild([&] (IBlockInputStream & child)
UInt64 start_time;
{
auto lock = get_lock();
start_time = info.total_stopwatch.elapsed();
}

forEachChild([&](IBlockInputStream & child) {
child.readSuffix();
return false;
});

readSuffixImpl();
info.updateExecutionTime(info.total_stopwatch.elapsed() - start_time);
{
auto lock = get_lock();
info.updateExecutionTime(info.total_stopwatch.elapsed() - start_time);
}
}


Expand Down Expand Up @@ -213,24 +235,23 @@ static bool handleOverflowMode(OverflowMode mode, const String & message, int co
{
switch (mode)
{
case OverflowMode::THROW:
throw Exception(message, code);
case OverflowMode::BREAK:
return false;
default:
throw Exception("Logical error: unknown overflow mode", ErrorCodes::LOGICAL_ERROR);
case OverflowMode::THROW:
throw Exception(message, code);
case OverflowMode::BREAK:
return false;
default:
throw Exception("Logical error: unknown overflow mode", ErrorCodes::LOGICAL_ERROR);
}
};


bool IProfilingBlockInputStream::checkTimeLimit()
bool IProfilingBlockInputStream::checkTimeLimit() const
{
if (limits.max_execution_time != 0
&& info.total_stopwatch.elapsed() > static_cast<UInt64>(limits.max_execution_time.totalMicroseconds()) * 1000)
return handleOverflowMode(limits.timeout_overflow_mode,
"Timeout exceeded: elapsed " + toString(info.total_stopwatch.elapsedSeconds())
+ " seconds, maximum: " + toString(limits.max_execution_time.totalMicroseconds() / 1000000.0),
ErrorCodes::TIMEOUT_EXCEEDED);
"Timeout exceeded: elapsed " + toString(info.total_stopwatch.elapsedSeconds())
+ " seconds, maximum: " + toString(limits.max_execution_time.totalMicroseconds() / 1000000.0),
ErrorCodes::TIMEOUT_EXCEEDED);

return true;
}
Expand All @@ -240,24 +261,28 @@ void IProfilingBlockInputStream::checkQuota(Block & block)
{
switch (limits.mode)
{
case LIMITS_TOTAL:
/// Checked in `progress` method.
break;
case LIMITS_TOTAL:
/// Checked in `progress` method.
break;

case LIMITS_CURRENT:
case LIMITS_CURRENT:
{
time_t current_time = time(nullptr);
double total_elapsed;
{
time_t current_time = time(nullptr);
double total_elapsed = info.total_stopwatch.elapsedSeconds();
auto lock = get_lock();
total_elapsed = info.total_stopwatch.elapsedSeconds();
}

quota->checkAndAddResultRowsBytes(current_time, block.rows(), block.bytes());
quota->checkAndAddExecutionTime(current_time, Poco::Timespan((total_elapsed - prev_elapsed) * 1000000.0));
quota->checkAndAddResultRowsBytes(current_time, block.rows(), block.bytes());
quota->checkAndAddExecutionTime(current_time, Poco::Timespan((total_elapsed - prev_elapsed) * 1000000.0));

prev_elapsed = total_elapsed;
break;
}
prev_elapsed = total_elapsed;
break;
}

default:
throw Exception("Logical error: unknown limits mode.", ErrorCodes::LOGICAL_ERROR);
default:
throw Exception("Logical error: unknown limits mode.", ErrorCodes::LOGICAL_ERROR);
}
}

Expand Down Expand Up @@ -287,48 +312,51 @@ void IProfilingBlockInputStream::progressImpl(const Progress & value)
{
switch (limits.size_limits.overflow_mode)
{
case OverflowMode::THROW:
{
if (limits.size_limits.max_rows && total_rows_estimate > limits.size_limits.max_rows)
throw Exception("Limit for rows to read exceeded: " + toString(total_rows_estimate)
+ " rows read (or to read), maximum: " + toString(limits.size_limits.max_rows),
ErrorCodes::TOO_MANY_ROWS);
else
throw Exception("Limit for (uncompressed) bytes to read exceeded: " + toString(progress.bytes)
+ " bytes read, maximum: " + toString(limits.size_limits.max_bytes),
ErrorCodes::TOO_MANY_BYTES);
break;
}
case OverflowMode::THROW:
{
if (limits.size_limits.max_rows && total_rows_estimate > limits.size_limits.max_rows)
throw Exception("Limit for rows to read exceeded: " + toString(total_rows_estimate)
+ " rows read (or to read), maximum: " + toString(limits.size_limits.max_rows),
ErrorCodes::TOO_MANY_ROWS);
else
throw Exception("Limit for (uncompressed) bytes to read exceeded: " + toString(progress.bytes)
+ " bytes read, maximum: " + toString(limits.size_limits.max_bytes),
ErrorCodes::TOO_MANY_BYTES);
break;
}

case OverflowMode::BREAK:
case OverflowMode::BREAK:
{
/// For `break`, we will stop only if so many rows were actually read, and not just supposed to be read.
if ((limits.size_limits.max_rows && progress.rows > limits.size_limits.max_rows)
|| (limits.size_limits.max_bytes && progress.bytes > limits.size_limits.max_bytes))
{
/// For `break`, we will stop only if so many rows were actually read, and not just supposed to be read.
if ((limits.size_limits.max_rows && progress.rows > limits.size_limits.max_rows)
|| (limits.size_limits.max_bytes && progress.bytes > limits.size_limits.max_bytes))
{
cancel(false);
}

break;
cancel(false);
}

default:
throw Exception("Logical error: unknown overflow mode", ErrorCodes::LOGICAL_ERROR);
break;
}

default:
throw Exception("Logical error: unknown overflow mode", ErrorCodes::LOGICAL_ERROR);
}
}

size_t total_rows = progress.total_rows;

if (limits.min_execution_speed || (total_rows && limits.timeout_before_checking_execution_speed != 0))
{
double total_elapsed = info.total_stopwatch.elapsedSeconds();

double total_elapsed;
{
auto lock = get_lock();
total_elapsed = info.total_stopwatch.elapsedSeconds();
}
if (total_elapsed > limits.timeout_before_checking_execution_speed.totalMicroseconds() / 1000000.0)
{
if (limits.min_execution_speed && progress.rows / total_elapsed < limits.min_execution_speed)
throw Exception("Query is executing too slow: " + toString(progress.rows / total_elapsed)
+ " rows/sec., minimum: " + toString(limits.min_execution_speed),
ErrorCodes::TOO_SLOW);
+ " rows/sec., minimum: " + toString(limits.min_execution_speed),
ErrorCodes::TOO_SLOW);

size_t total_rows = progress.total_rows;

Expand All @@ -339,9 +367,9 @@ void IProfilingBlockInputStream::progressImpl(const Progress & value)

if (estimated_execution_time_seconds > limits.max_execution_time.totalSeconds())
throw Exception("Estimated query execution time (" + toString(estimated_execution_time_seconds) + " seconds)"
+ " is too long. Maximum: " + toString(limits.max_execution_time.totalSeconds())
+ ". Estimated rows to process: " + toString(total_rows),
ErrorCodes::TOO_SLOW);
+ " is too long. Maximum: " + toString(limits.max_execution_time.totalSeconds())
+ ". Estimated rows to process: " + toString(total_rows),
ErrorCodes::TOO_SLOW);
}
}
}
Expand All @@ -363,8 +391,7 @@ void IProfilingBlockInputStream::cancel(bool kill)
if (!is_cancelled.compare_exchange_strong(old_val, true, std::memory_order_seq_cst, std::memory_order_relaxed))
return;

forEachProfilingChild([&] (IProfilingBlockInputStream & child)
{
forEachProfilingChild([&](IProfilingBlockInputStream & child) {
child.cancel(kill);
return false;
});
Expand All @@ -390,8 +417,7 @@ void IProfilingBlockInputStream::setProgressCallback(const ProgressCallback & ca
{
progress_callback = callback;

forEachProfilingChild([&] (IProfilingBlockInputStream & child)
{
forEachProfilingChild([&](IProfilingBlockInputStream & child) {
child.setProgressCallback(callback);
return false;
});
Expand All @@ -402,8 +428,7 @@ void IProfilingBlockInputStream::setProcessListElement(ProcessListElement * elem
{
process_list_elem = elem;

forEachProfilingChild([&] (IProfilingBlockInputStream & child)
{
forEachProfilingChild([&](IProfilingBlockInputStream & child) {
child.setProcessListElement(elem);
return false;
});
Expand All @@ -416,12 +441,9 @@ Block IProfilingBlockInputStream::getTotals()
return totals;

Block res;
forEachProfilingChild([&] (IProfilingBlockInputStream & child)
{
forEachProfilingChild([&](IProfilingBlockInputStream & child) {
res = child.getTotals();
if (res)
return true;
return false;
return static_cast<bool>(res);
});
return res;
}
Expand All @@ -432,14 +454,11 @@ Block IProfilingBlockInputStream::getExtremes()
return extremes;

Block res;
forEachProfilingChild([&] (IProfilingBlockInputStream & child)
{
forEachProfilingChild([&](IProfilingBlockInputStream & child) {
res = child.getExtremes();
if (res)
return true;
return false;
return static_cast<bool>(res);
});
return res;
}

}
} // namespace DB
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