NDB dbtux scan batch max 16->992 caused perf loss (235d0787) · Commits · Software / OSDI20 Artifacts / mariadb

ndb/src/kernel/blocks/dbtux/Dbtux.hpp

+12 −4

Original line number	Diff line number	Diff line
		@@ -404,8 +404,6 @@ private:
		Uint32 m_savePointId;
		// lock waited for or obtained and not yet passed to LQH
		Uint32 m_accLockOp;
		// locks obtained and passed to LQH but not yet returned by LQH
		Uint32 m_accLockOps[MaxAccLockOps];
		Uint8 m_readCommitted; // no locking
		Uint8 m_lockMode;
		Uint8 m_keyInfo;
		@@ -421,6 +419,13 @@ private:
		Uint32 nextList;
		};
		Uint32 prevList;
		/*
		* Locks obtained and passed to LQH but not yet returned by LQH.
		* The max was increased from 16 to 992 (default 64). Record max
		* ever used in this scan. TODO fix quadratic behaviour
		*/
		Uint32 m_maxAccLockOps;
		Uint32 m_accLockOps[MaxAccLockOps];
		ScanOp(ScanBoundPool& scanBoundPool);
		};
		typedef Ptr<ScanOp> ScanOpPtr;
		@@ -1028,15 +1033,18 @@ Dbtux::ScanOp::ScanOp(ScanBoundPool& scanBoundPool) :
		m_boundMax(scanBoundPool),
		m_scanPos(),
		m_scanEnt(),
		m_nodeScan(RNIL)
		m_nodeScan(RNIL),
		m_maxAccLockOps(0)
		{
		m_bound[0] = &m_boundMin;
		m_bound[1] = &m_boundMax;
		m_boundCnt[0] = 0;
		m_boundCnt[1] = 0;
		#ifdef VM_TRACE
		for (unsigned i = 0; i < MaxAccLockOps; i++) {
		m_accLockOps[i] = RNIL;
		m_accLockOps[i] = 0x1f1f1f1f;
		}
		#endif
		}

		// Dbtux::Index

ndb/src/kernel/blocks/dbtux/DbtuxScan.cpp

+11 −3

Original line number	Diff line number	Diff line
		@@ -917,7 +917,7 @@ Dbtux::scanClose(Signal* signal, ScanOpPtr scanPtr)
		ScanOp& scan = *scanPtr.p;
		ndbrequire(! scan.m_lockwait && scan.m_accLockOp == RNIL);
		// unlock all not unlocked by LQH
		for (unsigned i = 0; i < MaxAccLockOps; i++) {
		for (unsigned i = 0; i < scan.m_maxAccLockOps; i++) {
		if (scan.m_accLockOps[i] != RNIL) {
		jam();
		AccLockReq* const lockReq = (AccLockReq*)signal->getDataPtrSend();
		@@ -947,7 +947,7 @@ Dbtux::addAccLockOp(ScanOp& scan, Uint32 accLockOp)
		ndbrequire(accLockOp != RNIL);
		Uint32* list = scan.m_accLockOps;
		bool ok = false;
		for (unsigned i = 0; i < MaxAccLockOps; i++) {
		for (unsigned i = 0; i < scan.m_maxAccLockOps; i++) {
		ndbrequire(list[i] != accLockOp);
		if (! ok && list[i] == RNIL) {
		list[i] = accLockOp;
		@@ -955,6 +955,14 @@ Dbtux::addAccLockOp(ScanOp& scan, Uint32 accLockOp)
		// continue check for duplicates
		}
		}
		if (! ok) {
		unsigned i = scan.m_maxAccLockOps;
		if (i < MaxAccLockOps) {
		list[i] = accLockOp;
		ok = true;
		scan.m_maxAccLockOps = i + 1;
		}
		}
		ndbrequire(ok);
		}

		@@ -964,7 +972,7 @@ Dbtux::removeAccLockOp(ScanOp& scan, Uint32 accLockOp)
		ndbrequire(accLockOp != RNIL);
		Uint32* list = scan.m_accLockOps;
		bool ok = false;
		for (unsigned i = 0; i < MaxAccLockOps; i++) {
		for (unsigned i = 0; i < scan.m_maxAccLockOps; i++) {
		if (list[i] == accLockOp) {
		list[i] = RNIL;
		ok = true;

ndb/src/kernel/blocks/dbtux/Times.txt

+9 −1

Original line number	Diff line number	Diff line
		@@ -13,7 +13,7 @@ case c: full scan: index on PK Unsigned
		testOIBasic -case v -table 1 -index 1 -fragtype small -threads 10 -rows 100000 -subloop 1 -nologging

		case d: scan 1 tuple via EQ: index on PK Unsigned
		testOIBasic -case w -table 1 -index 1 -fragtype small -threads 10 -rows 100000 -samples 10000 -subloop 1 -nologging -v2
		testOIBasic -case w -table 1 -index 1 -fragtype small -threads 10 -rows 100000 -samples 50000 -subloop 1 -nologging -v2

		a, b
		1 million rows, pk update without index, pk update with index
		@@ -132,4 +132,12 @@ optim 17 mc02/a 35 ms 52 ms 49 pct
		wl-1942 mc02/a 35 ms 52 ms 49 pct
		mc02/b 42 ms 75 ms 76 pct

		before mc02/c 5 ms 13 ms 126 pct
		mc02/d 134 ms 238 ms 78 pct

		after mc02/c 5 ms 10 ms 70 pct
		mc02/d 178 ms 242 ms 69 pct

		[ prelim preformance fix for max batch size 16 -> 992 ]

		vim: set et:

ndb/test/ndbapi/testOIBasic.cpp

+22 −0

Original line number	Diff line number	Diff line
		@@ -54,6 +54,7 @@ struct Opt {
		unsigned m_samples;
		unsigned m_scanbat;
		unsigned m_scanpar;
		unsigned m_scanstop;
		unsigned m_seed;
		unsigned m_subloop;
		const char* m_table;
		@@ -80,6 +81,7 @@ struct Opt {
		m_samples(0),
		m_scanbat(0),
		m_scanpar(0),
		m_scanstop(0),
		m_seed(0),
		m_subloop(4),
		m_table(0),
		@@ -708,6 +710,7 @@ struct Con {
		int nextScanResult(bool fetchAllowed, bool& deadlock);
		int updateScanTuple(Con& con2);
		int deleteScanTuple(Con& con2);
		void closeScan();
		void closeTransaction();
		void printerror(NdbOut& out);
		};
		@@ -894,12 +897,22 @@ Con::deleteScanTuple(Con& con2)
		return 0;
		}

		void
		Con::closeScan()
		{
		assert(m_resultset != 0);
		m_resultset->close();
		m_scanop = 0, m_indexscanop = 0, m_resultset = 0;

		}

		void
		Con::closeTransaction()
		{
		assert(m_ndb != 0 && m_tx != 0);
		m_ndb->closeTransaction(m_tx);
		m_tx = 0, m_op = 0;
		m_scanop = 0, m_indexscanop = 0, m_resultset = 0;
		}

		void
		@@ -2538,6 +2551,10 @@ scanupdatetable(Par par)
		LL1("scanupdatetable: stop on deadlock");
		break;
		}
		if (par.m_scanstop != 0 && urandom(par.m_scanstop) == 0) {
		con.closeScan();
		break;
		}
		do {
		unsigned i = (unsigned)-1;
		CHK(set2.getkey(par, &i) == 0);
		@@ -2618,6 +2635,10 @@ scanupdateindex(Par par, const ITab& itab, const BSet& bset)
		LL1("scanupdateindex: stop on deadlock");
		break;
		}
		if (par.m_scanstop != 0 && urandom(par.m_scanstop) == 0) {
		con.closeScan();
		break;
		}
		do {
		unsigned i = (unsigned)-1;
		CHK(set2.getkey(par, &i) == 0);
		@@ -2782,6 +2803,7 @@ mixedoperations(Par par)
		{
		par.m_dups = true;
		par.m_deadlock = true;
		par.m_scanstop = par.m_totrows; // randomly close scans
		unsigned sel = urandom(10);
		if (sel < 2) {
		CHK(pkdelete(par) == 0);