3 * Transaction profiling for contention
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6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
18 * http://www.gnu.org/copyleft/gpl.html
24 namespace Wikimedia\Rdbms
;
26 use Psr\Log\LoggerInterface
;
27 use Psr\Log\LoggerAwareInterface
;
28 use Psr\Log\NullLogger
;
32 * Helper class that detects high-contention DB queries via profiling calls
34 * This class is meant to work with an IDatabase object, which manages queries
38 class TransactionProfiler
implements LoggerAwareInterface
{
39 /** @var float Seconds */
40 protected $dbLockThreshold = 3.0;
41 /** @var float Seconds */
42 protected $eventThreshold = .25;
44 protected $silenced = false;
46 /** @var array transaction ID => (write start time, list of DBs involved) */
47 protected $dbTrxHoldingLocks = [];
48 /** @var array transaction ID => list of (query name, start time, end time) */
49 protected $dbTrxMethodTimes = [];
65 'readQueryTime' => INF
,
66 'writeQueryTime' => INF
69 protected $expectBy = [];
72 * @var LoggerInterface
76 public function __construct() {
77 $this->setLogger( new NullLogger() );
80 public function setLogger( LoggerInterface
$logger ) {
81 $this->logger
= $logger;
85 * @param bool $value New value
86 * @return bool Old value
89 public function setSilenced( $value ) {
90 $old = $this->silenced
;
91 $this->silenced
= $value;
97 * Set performance expectations
99 * With conflicting expectations, the most narrow ones will be used
101 * @param string $event (writes,queries,conns,mConns)
102 * @param integer $value Maximum count of the event
103 * @param string $fname Caller
106 public function setExpectation( $event, $value, $fname ) {
107 $this->expect
[$event] = isset( $this->expect
[$event] )
108 ?
min( $this->expect
[$event], $value )
110 if ( $this->expect
[$event] == $value ) {
111 $this->expectBy
[$event] = $fname;
116 * Set multiple performance expectations
118 * With conflicting expectations, the most narrow ones will be used
120 * @param array $expects Map of (event => limit)
124 public function setExpectations( array $expects, $fname ) {
125 foreach ( $expects as $event => $value ) {
126 $this->setExpectation( $event, $value, $fname );
131 * Reset performance expectations and hit counters
135 public function resetExpectations() {
136 foreach ( $this->hits
as &$val ) {
140 foreach ( $this->expect
as &$val ) {
144 $this->expectBy
= [];
148 * Mark a DB as having been connected to with a new handle
150 * Note that there can be multiple connections to a single DB.
152 * @param string $server DB server
153 * @param string $db DB name
154 * @param bool $isMaster
156 public function recordConnection( $server, $db, $isMaster ) {
157 // Report when too many connections happen...
158 if ( $this->hits
['conns']++
== $this->expect
['conns'] ) {
159 $this->reportExpectationViolated( 'conns', "[connect to $server ($db)]" );
161 if ( $isMaster && $this->hits
['masterConns']++
== $this->expect
['masterConns'] ) {
162 $this->reportExpectationViolated( 'masterConns', "[connect to $server ($db)]" );
167 * Mark a DB as in a transaction with one or more writes pending
169 * Note that there can be multiple connections to a single DB.
171 * @param string $server DB server
172 * @param string $db DB name
173 * @param string $id ID string of transaction
175 public function transactionWritingIn( $server, $db, $id ) {
176 $name = "{$server} ({$db}) (TRX#$id)";
177 if ( isset( $this->dbTrxHoldingLocks
[$name] ) ) {
178 $this->logger
->info( "Nested transaction for '$name' - out of sync." );
180 $this->dbTrxHoldingLocks
[$name] = [
181 'start' => microtime( true ),
182 'conns' => [], // all connections involved
184 $this->dbTrxMethodTimes
[$name] = [];
186 foreach ( $this->dbTrxHoldingLocks
as $name => &$info ) {
187 // Track all DBs in transactions for this transaction
188 $info['conns'][$name] = 1;
193 * Register the name and time of a method for slow DB trx detection
195 * This assumes that all queries are synchronous (non-overlapping)
197 * @param string $query Function name or generalized SQL
198 * @param float $sTime Starting UNIX wall time
199 * @param bool $isWrite Whether this is a write query
200 * @param integer $n Number of affected rows
202 public function recordQueryCompletion( $query, $sTime, $isWrite = false, $n = 0 ) {
203 $eTime = microtime( true );
204 $elapsed = ( $eTime - $sTime );
206 if ( $isWrite && $n > $this->expect
['maxAffected'] ) {
208 "Query affected $n row(s):\n" . $query . "\n" .
209 ( new RuntimeException() )->getTraceAsString() );
212 // Report when too many writes/queries happen...
213 if ( $this->hits
['queries']++
== $this->expect
['queries'] ) {
214 $this->reportExpectationViolated( 'queries', $query );
216 if ( $isWrite && $this->hits
['writes']++
== $this->expect
['writes'] ) {
217 $this->reportExpectationViolated( 'writes', $query );
219 // Report slow queries...
220 if ( !$isWrite && $elapsed > $this->expect
['readQueryTime'] ) {
221 $this->reportExpectationViolated( 'readQueryTime', $query, $elapsed );
223 if ( $isWrite && $elapsed > $this->expect
['writeQueryTime'] ) {
224 $this->reportExpectationViolated( 'writeQueryTime', $query, $elapsed );
227 if ( !$this->dbTrxHoldingLocks
) {
230 } elseif ( !$isWrite && $elapsed < $this->eventThreshold
) {
231 // Not an important query nor slow enough
235 foreach ( $this->dbTrxHoldingLocks
as $name => $info ) {
236 $lastQuery = end( $this->dbTrxMethodTimes
[$name] );
238 // Additional query in the trx...
239 $lastEnd = $lastQuery[2];
240 if ( $sTime >= $lastEnd ) { // sanity check
241 if ( ( $sTime - $lastEnd ) > $this->eventThreshold
) {
242 // Add an entry representing the time spent doing non-queries
243 $this->dbTrxMethodTimes
[$name][] = [ '...delay...', $lastEnd, $sTime ];
245 $this->dbTrxMethodTimes
[$name][] = [ $query, $sTime, $eTime ];
248 // First query in the trx...
249 if ( $sTime >= $info['start'] ) { // sanity check
250 $this->dbTrxMethodTimes
[$name][] = [ $query, $sTime, $eTime ];
257 * Mark a DB as no longer in a transaction
259 * This will check if locks are possibly held for longer than
260 * needed and log any affected transactions to a special DB log.
261 * Note that there can be multiple connections to a single DB.
263 * @param string $server DB server
264 * @param string $db DB name
265 * @param string $id ID string of transaction
266 * @param float $writeTime Time spent in write queries
267 * @param integer $affected Number of rows affected by writes
269 public function transactionWritingOut( $server, $db, $id, $writeTime = 0.0, $affected = 0 ) {
270 $name = "{$server} ({$db}) (TRX#$id)";
271 if ( !isset( $this->dbTrxMethodTimes
[$name] ) ) {
272 $this->logger
->info( "Detected no transaction for '$name' - out of sync." );
278 // Warn if too much time was spend writing...
279 if ( $writeTime > $this->expect
['writeQueryTime'] ) {
280 $this->reportExpectationViolated(
282 "[transaction $id writes to {$server} ({$db})]",
287 // Warn if too many rows were changed...
288 if ( $affected > $this->expect
['maxAffected'] ) {
289 $this->reportExpectationViolated(
291 "[transaction $id writes to {$server} ({$db})]",
295 // Fill in the last non-query period...
296 $lastQuery = end( $this->dbTrxMethodTimes
[$name] );
298 $now = microtime( true );
299 $lastEnd = $lastQuery[2];
300 if ( ( $now - $lastEnd ) > $this->eventThreshold
) {
301 $this->dbTrxMethodTimes
[$name][] = [ '...delay...', $lastEnd, $now ];
304 // Check for any slow queries or non-query periods...
305 foreach ( $this->dbTrxMethodTimes
[$name] as $info ) {
306 $elapsed = ( $info[2] - $info[1] );
307 if ( $elapsed >= $this->dbLockThreshold
) {
314 foreach ( $this->dbTrxMethodTimes
[$name] as $i => $info ) {
315 list( $query, $sTime, $end ) = $info;
316 $trace .= sprintf( "%d\t%.6f\t%s\n", $i, ( $end - $sTime ), $query );
318 $this->logger
->info( "Sub-optimal transaction on DB(s) [{dbs}]: \n{trace}", [
319 'dbs' => implode( ', ', array_keys( $this->dbTrxHoldingLocks
[$name]['conns'] ) ),
323 unset( $this->dbTrxHoldingLocks
[$name] );
324 unset( $this->dbTrxMethodTimes
[$name] );
328 * @param string $expect
329 * @param string $query
330 * @param string|float|int $actual [optional]
332 protected function reportExpectationViolated( $expect, $query, $actual = null ) {
333 if ( $this->silenced
) {
337 $n = $this->expect
[$expect];
338 $by = $this->expectBy
[$expect];
339 $actual = ( $actual !== null ) ?
" (actual: $actual)" : "";
342 "Expectation ($expect <= $n) by $by not met$actual:\n$query\n" .
343 ( new RuntimeException() )->getTraceAsString()