set mysqld tmpdir to avoid race condition with multiple mysql instanc…

…es on a single host

config/mycnf/default.cnf

@@ -48,13 +48,15 @@ skip-name-resolve
 # some extra work to skip mangled transactions or fudge the slave start
 skip_slave_start
 slave_net_timeout = 60
+slave_load_tmpdir = {{.SlaveLoadTmpDir}}
 slow-query-log
 slow-query-log-file = {{.SlowLogPath}}
 socket = {{.SocketFile}}
 sort_buffer_size = 2M
 table_cache = 2048
 thread_cache = 200
 thread_concurrency = 24
+tmpdir = {{.TmpDir}}
 tmp_table_size = 32M
 transaction-isolation = REPEATABLE-READ
 # READ-COMMITTED would be better, but mysql 5.1 disables this with statement based replication

go/vt/mysqlctl/mycnf.go

@@ -37,6 +37,8 @@ type Mycnf struct {
 	BinLogIndexPath       string
 	MasterInfoFile        string
 	PidFile               string
+	TmpDir                string
+	SlaveLoadTmpDir       string
 	mycnfMap              map[string]string
 }
 

go/vt/mysqlctl/mycnf_gen.go

@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-/*
-  Generate my.cnf files from templates.
-*/
+//  Generate my.cnf files from templates.
 
 package mysqlctl
 
@@ -34,13 +32,11 @@ const (
 	snapshotDir      = "snapshot"
 )
 
-/*
-NewMycnf fills the Mycnf structure with vt root paths and derived values.
-This is used to fill out the cnfTemplate values and generate my.cnf.
-uid is a unique id for a particular tablet - it must be unique within the
-tabletservers deployed within a keyspace, lest there be collisions on disk.
-mysqldPort needs to be unique per instance per machine.
-*/
+// NewMycnf fills the Mycnf structure with vt root paths and derived values.
+// This is used to fill out the cnfTemplate values and generate my.cnf.
+// uid is a unique id for a particular tablet - it must be unique within the
+// tabletservers deployed within a keyspace, lest there be collisions on disk.
+// mysqldPort needs to be unique per instance per machine.
 func NewMycnf(uid uint32, mysqlPort int, vtRepl VtReplParams) *Mycnf {
 	cnf := new(Mycnf)
 	tabletDir := TabletDir(uid)
@@ -63,6 +59,8 @@ func NewMycnf(uid uint32, mysqlPort int, vtRepl VtReplParams) *Mycnf {
 	cnf.BinLogIndexPath = cnf.BinLogPath + ".index"
 	cnf.MasterInfoFile = path.Join(tabletDir, "master.info")
 	cnf.PidFile = path.Join(tabletDir, "mysql.pid")
+	cnf.TmpDir = path.Join(tabletDir, "tmp")
+	cnf.SlaveLoadTmpDir = cnf.TmpDir
 	return cnf
 }
 
@@ -87,14 +85,13 @@ func DirectoryList(cnf *Mycnf) []string {
 		cnf.DataDir,
 		cnf.InnodbDataHomeDir,
 		cnf.InnodbLogGroupHomeDir,
+		cnf.TmpDir,
 		path.Join(TabletDir(cnf.ServerId), relayLogDir),
 		path.Join(TabletDir(cnf.ServerId), binLogDir),
 	}
 }
 
-/*
-  Join cnf files cnfPaths and subsitute in the right values.
-*/
+// Join cnf files cnfPaths and subsitute in the right values.
 func MakeMycnf(cnfFiles []string, mycnf *Mycnf, header string) (string, error) {
 	myTemplateSource := new(bytes.Buffer)
 	for _, line := range strings.Split(header, "\n") {
@@ -122,9 +119,8 @@ func MakeMycnf(cnfFiles []string, mycnf *Mycnf, header string) (string, error) {
 	return mycnfData.String(), nil
 }
 
-/* Create a config for this instance. Search cnfFiles for the appropriate
-cnf template files.
-*/
+// Create a config for this instance. Search cnfFiles for the
+// appropriate cnf template files.
 func MakeMycnfForMysqld(mysqld *Mysqld, cnfFiles, header string) (string, error) {
 	// FIXME(msolomon) determine config list from mysqld struct
 	cnfs := []string{"default", "master", "replica"}