octoleo/gh-ost
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Merge 11540b453b into b7db8c6ca7

Browse Source
This commit is contained in:
cenkore 2023-04-20 16:59:05 +00:00 committed by GitHub
commit da8a6a48fe
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 108 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
go/base/context.go
View File

@ -232,6 +232,8 @@ type MigrationContext struct {
recentBinlogCoordinates mysql.BinlogCoordinates
AllowSetupMetadataLockInstruments bool
Log Logger
}

2
go/cmd/gh-ost/main.go
View File

@ -134,7 +134,7 @@ func main() {
flag.Int64Var(&migrationContext.HooksStatusIntervalSec, "hooks-status-interval", 60, "how many seconds to wait between calling onStatus hook")
flag.UintVar(&migrationContext.ReplicaServerId, "replica-server-id", 99999, "server id used by gh-ost process. Default: 99999")
flag.BoolVar(&migrationContext.AllowSetupMetadataLockInstruments, "allow-setup-metadata-lock-instruments", false, "validate rename session acquiring lock whether is original table before unlock tables in cut-over phase")
maxLoad := flag.String("max-load", "", "Comma delimited status-name=threshold. e.g: 'Threads_running=100,Threads_connected=500'. When status exceeds threshold, app throttles writes")
criticalLoad := flag.String("critical-load", "", "Comma delimited status-name=threshold, same format as --max-load. When status exceeds threshold, app panics and quits")
flag.Int64Var(&migrationContext.CriticalLoadIntervalMilliseconds, "critical-load-interval-millis", 0, "When 0, migration immediately bails out upon meeting critical-load. When non-zero, a second check is done after given interval, and migration only bails out if 2nd check still meets critical load")

82
go/logic/applier.go
View File

@ -7,6 +7,7 @@ package logic
import (
gosql "database/sql"
"errors"
"fmt"
"strings"
"sync/atomic"
@ -416,6 +417,24 @@ func (this *Applier) WriteChangelogState(value string) (string, error) {
return this.WriteAndLogChangelog("state", value)
}
func (this *Applier) EnableMetadataLockInstrument() (err error) {
query := `select /*+ MAX_EXECUTION_TIME(300) */ ENABLED, TIMED from performance_schema.setup_instruments WHERE NAME = 'wait/lock/metadata/sql/mdl'`
var enabled, timed string
if err = this.db.QueryRow(query).Scan(&enabled, &timed); err != nil {
return this.migrationContext.Log.Errorf("query performance_schema.setup_instruments with name wait/lock/metadata/sql/mdl error: %s", err)
}
if strings.EqualFold(enabled, "YES") && strings.EqualFold(timed, "YES") {
this.migrationContext.Log.Infof("instrument wait/lock/metadata/sql/mdl already has been enabled")
return nil
}
this.migrationContext.Log.Infof("instrument wait/lock/metadata/sql/mdl state: enabled %s, timed %s", enabled, timed)
if _, err = this.db.Exec(`UPDATE performance_schema.setup_instruments SET ENABLED = 'YES', TIMED = 'YES' WHERE NAME = 'wait/lock/metadata/sql/mdl'`); err != nil {
return this.migrationContext.Log.Errorf("enable instrument wait/lock/metadata/sql/mdl error: %s", err)
}
this.migrationContext.Log.Infof("instrument wait/lock/metadata/sql/mdl enabled")
return nil
}
// InitiateHeartbeat creates a heartbeat cycle, writing to the changelog table.
// This is done asynchronously
func (this *Applier) InitiateHeartbeat() {
@ -934,7 +953,7 @@ func (this *Applier) CreateAtomicCutOverSentryTable() error {
}
// AtomicCutOverMagicLock
func (this *Applier) AtomicCutOverMagicLock(sessionIdChan chan int64, tableLocked chan<- error, okToUnlockTable <-chan bool, tableUnlocked chan<- error) error {
func (this *Applier) AtomicCutOverMagicLock(sessionIdChan chan int64, tableLocked chan<- error, okToUnlockTable <-chan bool, tableUnlocked chan<- error, okToDropSentryTable <-chan bool, dropSentryTableDone chan<- bool) error {
tx, err := this.db.Begin()
if err != nil {
tableLocked <- err
@ -1003,7 +1022,16 @@ func (this *Applier) AtomicCutOverMagicLock(sessionIdChan chan int64, tableLocke
// The cut-over phase will proceed to apply remaining backlog onto ghost table,
// and issue RENAME. We wait here until told to proceed.
<-okToUnlockTable
// we should make sure that the whole lock tables duration(include wait channel cost) not higher than rename session timeout.
// receive timeout channel, Rename session already has timeout&quit
select {
case <-okToDropSentryTable:
this.migrationContext.Log.Infof("Receive drop magic table channel, drop table %s.%s now", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.GetOldTableName()))
case <-time.After(time.Duration(tableLockTimeoutSeconds)*time.Second - time.Since(this.migrationContext.LockTablesStartTime)):
this.migrationContext.Log.Warningf("Wait drop magic table channel timeout, drop table %s.%s forcefully now. Noteworthy, it is unreasonable, timeout was used for foolproof, but normally it should not be here.", sql.EscapeName(this.migrationContext.DatabaseName), sql.EscapeName(this.migrationContext.GetOldTableName()))
}
this.migrationContext.Log.Infof("Will now proceed to drop magic table and unlock tables")
// The magic table is here because we locked it. And we are the only ones allowed to drop it.
@ -1019,6 +1047,16 @@ func (this *Applier) AtomicCutOverMagicLock(sessionIdChan chan int64, tableLocke
// We DO NOT return here because we must `UNLOCK TABLES`!
}
// Anyway, send dropSentryTableDone channel here
dropSentryTableDone <- true
// receive timeout channel, Rename session already has timeout&quit
select {
case <-okToUnlockTable:
this.migrationContext.Log.Infof("Receive unlock table channel, unlock tables now")
case <-time.After(time.Duration(tableLockTimeoutSeconds)*time.Second - time.Since(this.migrationContext.LockTablesStartTime)):
this.migrationContext.Log.Warningf("Wait unlock table channel timeout, unlock tables forcefully now. Noteworthy, it is unreasonable, timeout was used for foolproof, but normally it should not be here.")
}
// Tables still locked
this.migrationContext.Log.Infof("Releasing lock from %s.%s, %s.%s",
sql.EscapeName(this.migrationContext.DatabaseName),
@ -1079,6 +1117,46 @@ func (this *Applier) AtomicCutoverRename(sessionIdChan chan int64, tablesRenamed
return nil
}
// ValidateGhostTableLocked validate original table has been locked via wait/lock/metadata/sql/mdl instrument.
// return error means the ghost table has not been locked by rename session which is not expected. Need kill rename session, unlock table try again later.
func (this *Applier) ValidateGhostTableLocked(renameSessionId int64) (err error) {
var schema, object, state, info string
query := `select /*+ MAX_EXECUTION_TIME(300) */ ifnull(a.object_schema,''),a.object_name,b.PROCESSLIST_STATE,b.PROCESSLIST_INFO from performance_schema.metadata_locks a join performance_schema.threads b on a.owner_thread_id=b.thread_id where b.processlist_id=? and a.lock_status='PENDING';`
// Not strictly validate here
if err := this.db.QueryRow(query, renameSessionId).Scan(&schema, &object, &state, &info); err != nil {
if errors.Is(err, gosql.ErrNoRows) {
this.migrationContext.Log.Warningf("query metadata locks returns %s, perhaps instrument wait/lock/metadata/sql/mdl not enabled, enable it via -allow-setup-metadata-lock-instruments", err)
}
this.migrationContext.Log.Warningf("Grabbing rename session acquire metadata lock error: %s, query:%s", err, query)
} else {
this.migrationContext.Log.Infof("Grabbing rename session acquire metadata lock is schema:%s, object:%s, state:%s, info: %s", schema, object, state, info)
if !strings.EqualFold(strings.ToLower(object), strings.ToLower(this.migrationContext.OriginalTableName)) {
return this.migrationContext.Log.Errorf("Expect rename session %d acquiring table metadata lock is %s.%s, but got %s.%s",
renameSessionId,
sql.EscapeName(this.migrationContext.DatabaseName),
sql.EscapeName(this.migrationContext.OriginalTableName),
sql.EscapeName(schema),
sql.EscapeName(object))
}
}
return nil
}
// KillRenameSession Kill rename session while ghost table not locked.
// Check rename session id whether is an expect process before execute kill command.
func (this *Applier) KillRenameSession(renameSessionId int64) (err error) {
if err := this.ExpectProcess(renameSessionId, "metadata lock", "rename"); err != nil {
return err
}
this.migrationContext.Log.Infof("Starting kill rename session %d", renameSessionId)
query := fmt.Sprintf(`kill /* gh-ost */ %d`, renameSessionId)
if _, err := this.db.Exec(query); err != nil {
return this.migrationContext.Log.Errorf("kill rename session %d error %s, anyway starting release original table now", renameSessionId, err)
}
this.migrationContext.Log.Infof("Kill rename session %d done", renameSessionId)
return nil
}
func (this *Applier) ShowStatusVariable(variableName string) (result int64, err error) {
query := fmt.Sprintf(`show global status like '%s'`, variableName)
if err := this.db.QueryRow(query).Scan(&variableName, &result); err != nil {

27
go/logic/migrator.go
View File

@ -638,7 +638,10 @@ func (this *Migrator) atomicCutOver() (err error) {
defer atomic.StoreInt64(&this.migrationContext.InCutOverCriticalSectionFlag, 0)
okToUnlockTable := make(chan bool, 4)
okToDropSentryTable := make(chan bool, 4)
dropSentryTableDone := make(chan bool, 2)
defer func() {
okToDropSentryTable <- true
okToUnlockTable <- true
}()
@ -648,7 +651,7 @@ func (this *Migrator) atomicCutOver() (err error) {
tableLocked := make(chan error, 2)
tableUnlocked := make(chan error, 2)
go func() {
if err := this.applier.AtomicCutOverMagicLock(lockOriginalSessionIdChan, tableLocked, okToUnlockTable, tableUnlocked); err != nil {
if err := this.applier.AtomicCutOverMagicLock(lockOriginalSessionIdChan, tableLocked, okToUnlockTable, tableUnlocked, okToDropSentryTable, dropSentryTableDone); err != nil {
this.migrationContext.Log.Errore(err)
}
}()
@ -674,6 +677,7 @@ func (this *Migrator) atomicCutOver() (err error) {
if err := this.applier.AtomicCutoverRename(renameSessionIdChan, tablesRenamed); err != nil {
// Abort! Release the lock
atomic.StoreInt64(&tableRenameKnownToHaveFailed, 1)
okToDropSentryTable <- true
okToUnlockTable <- true
}
}()
@ -691,6 +695,7 @@ func (this *Migrator) atomicCutOver() (err error) {
// Wait for the RENAME to appear in PROCESSLIST
if err := this.retryOperation(waitForRename, true); err != nil {
// Abort! Release the lock
okToDropSentryTable <- true
okToUnlockTable <- true
return err
}
@ -703,9 +708,20 @@ func (this *Migrator) atomicCutOver() (err error) {
}
this.migrationContext.Log.Infof("Connection holding lock on original table still exists")
okToDropSentryTable <- true
<-dropSentryTableDone
if err := this.applier.ValidateGhostTableLocked(renameSessionId); err != nil {
// Abort! Kill Rename session and release the lock
if err := this.applier.KillRenameSession(renameSessionId); err != nil {
this.migrationContext.Log.Errore(err)
}
okToUnlockTable <- true
return err
}
// Now that we've found the RENAME blocking, AND the locking connection still alive,
// we know it is safe to proceed to release the lock
okToUnlockTable <- true
// BAM! magic table dropped, original table lock is released
// -> RENAME released -> queries on original are unblocked.
@ -1146,6 +1162,13 @@ func (this *Migrator) initiateApplier() error {
}
}
this.applier.WriteChangelogState(string(GhostTableMigrated))
if this.migrationContext.AllowSetupMetadataLockInstruments {
if err := this.applier.EnableMetadataLockInstrument(); err != nil {
this.migrationContext.Log.Errorf("Unable to enable metadata lock instrument, see further error details. Bailing out")
return err
}
}
go this.applier.InitiateHeartbeat()
return nil
}