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*: reduce ResetContextOfStmt() object allocation #26241

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merged 12 commits into from
Aug 9, 2021
Merged

*: reduce ResetContextOfStmt() object allocation #26241

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7d025ef
*: reduce ResetContextOfStmt() object allocation
tiancaiamao Jul 14, 2021
8f78614
Merge branch 'master' into optimize-reset-stmtctx
tiancaiamao Jul 14, 2021
836721b
make golint happy
tiancaiamao Jul 14, 2021
f88c5ae
Merge branch 'master' into optimize-reset-stmtctx
tiancaiamao Jul 19, 2021
e42c334
Merge branch 'master' into optimize-reset-stmtctx
ti-chi-bot Aug 3, 2021
46741f5
Merge branch 'master' into optimize-reset-stmtctx
ti-chi-bot Aug 3, 2021
4398666
Merge branch 'master' into optimize-reset-stmtctx
ti-chi-bot Aug 3, 2021
c3d89d4
Merge branch 'master' into optimize-reset-stmtctx
tiancaiamao Aug 6, 2021
08cff74
Merge branch 'master' into optimize-reset-stmtctx
ti-chi-bot Aug 6, 2021
4dce213
Merge branch 'master' into optimize-reset-stmtctx
ti-chi-bot Aug 6, 2021
b7d258c
Merge branch 'master' into optimize-reset-stmtctx
tiancaiamao Aug 9, 2021
e3fbf8f
Merge branch 'master' into optimize-reset-stmtctx
tiancaiamao Aug 9, 2021
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16 changes: 11 additions & 5 deletions executor/executor.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1656,12 +1656,18 @@ func (e *UnionExec) Close() error {
// Before every execution, we must clear statement context.
func ResetContextOfStmt(ctx sessionctx.Context, s ast.StmtNode) (err error) {
vars := ctx.GetSessionVars()
sc := &stmtctx.StatementContext{
TimeZone: vars.Location(),
TaskID: stmtctx.AllocateTaskID(),
CTEStorageMap: map[int]*CTEStorages{},
IsStaleness: false,
var sc *stmtctx.StatementContext
if vars.TxnCtx.CouldRetry {
// Must construct new statement context object, the retry history need context for every statement.
// TODO: Maybe one day we can get rid of transaction retry, then this logic can be deleted.
sc = &stmtctx.StatementContext{}
} else {
sc = vars.InitStatementContext()
}
sc.TimeZone = vars.Location()
sc.TaskID = stmtctx.AllocateTaskID()
sc.CTEStorageMap = map[int]*CTEStorages{}
sc.IsStaleness = false

sc.InitMemTracker(memory.LabelForSQLText, vars.MemQuotaQuery)
sc.InitDiskTracker(memory.LabelForSQLText, -1)
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1 change: 0 additions & 1 deletion executor/write_test.go
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Expand Up @@ -2169,7 +2169,6 @@ func (s *testSuite4) TestLoadData(c *C) {
{[]byte("\t2\t3"), []byte("\t4\t5"), nil, []byte("\t2\t3\t4\t5"), "Records: 0 Deleted: 0 Skipped: 0 Warnings: 0"},
}
checkCases(tests, ld, c, tk, ctx, selectSQL, deleteSQL)
c.Assert(sc.WarningCount(), Equals, uint16(1))
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This check is incorrect. The warnings is reset after the next statement.

The correct behavior should be check warning immediately after a statement.
The old code rely on every time a new statement context is allocated ... so even it does not checked immediately, the data is not overwritten.


// lines starting symbol is "" and terminated symbol length is 2, InsertData returns data is nil
ld.LinesInfo.Terminated = "||"
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2 changes: 0 additions & 2 deletions infoschema/tables_test.go
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Expand Up @@ -543,7 +543,6 @@ func (s *testTableSuite) TestSomeTables(c *C) {
Command: byte(1),
Digest: "abc1",
State: 1,
StmtCtx: tk.Se.GetSessionVars().StmtCtx,
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Take out tk.Se.GetSessionVars().StmtCtx for future use is not correct, it's not a snapshot.
The correct usage should be Lock -> Read data -> Unlock for process info ...
See #26196

}
sm.processInfoMap[2] = &util.ProcessInfo{
ID: 2,
Expand All @@ -553,7 +552,6 @@ func (s *testTableSuite) TestSomeTables(c *C) {
Digest: "abc2",
State: 2,
Info: strings.Repeat("x", 101),
StmtCtx: tk.Se.GetSessionVars().StmtCtx,
CurTxnStartTS: 410090409861578752,
}
tk.Se.SetSessionManager(sm)
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12 changes: 12 additions & 0 deletions sessionctx/variable/session.go
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Expand Up @@ -863,6 +863,18 @@ type SessionVars struct {

// TemporaryTableData stores committed kv values for temporary table for current session.
TemporaryTableData kv.MemBuffer

// cached is used to optimze the object allocation.
cached struct {
curr int8
data [2]stmtctx.StatementContext
}
}

func (s *SessionVars) InitStatementContext() *stmtctx.StatementContext {
s.cached.curr = (s.cached.curr + 1) % 2
s.cached.data[s.cached.curr] = stmtctx.StatementContext{}
return &s.cached.data[s.cached.curr]
}

// AllocMPPTaskID allocates task id for mpp tasks. It will reset the task id if the query's
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