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fix(Dgraph): Stop forcing RAM mode for the write-ahead log. #6142

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merged 5 commits into from
Aug 21, 2020
Merged

fix(Dgraph): Stop forcing RAM mode for the write-ahead log. #6142

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e990c7a
Stop forcing RAM mode for the w directory.
martinmr Aug 6, 2020
9db0baa
Merge branch 'master' into martinmr/w-mmap
martinmr Aug 18, 2020
882f091
Merge branch 'master' into martinmr/w-mmap
martinmr Aug 20, 2020
4549e0f
Add flags for setting badger options for wal separately.
martinmr Aug 20, 2020
9e6e2da
Merge flags.
martinmr Aug 21, 2020
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13 changes: 11 additions & 2 deletions dgraph/cmd/alpha/run.go
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Original file line number Diff line number Diff line change
Expand Up @@ -105,11 +105,18 @@ they form a Raft group and provide synchronous replication.

// Options around how to set up Badger.
flag.String("badger.tables", "mmap",
"[ram, mmap, disk] Specifies how Badger LSM tree is stored. "+
"[ram, mmap, disk] Specifies how Badger LSM tree is stored for the postings directory. "+
"Option sequence consume most to least RAM while providing best to worst read "+
"performance respectively.")
flag.String("badger.vlog", "mmap",
"[mmap, disk] Specifies how Badger Value log is stored."+
"[mmap, disk] Specifies how Badger Value log is stored for the postings directory."+
" mmap consumes more RAM, but provides better performance.")
flag.String("badger.wal_tables", "mmap",
"[ram, mmap, disk] Specifies how Badger LSM tree is stored for the write-ahead log. "+
"Option sequence consume most to least RAM while providing best to worst read "+
"performance respectively.")
flag.String("badger.wal_vlog", "mmap",
"[mmap, disk] Specifies how Badger Value log is stored for the write-ahead log."+
" mmap consumes more RAM, but provides better performance.")
flag.Int("badger.compression_level", 3,
"The compression level for Badger. A higher value uses more resources.")
Expand Down Expand Up @@ -575,6 +582,8 @@ func run() {
opts := worker.Options{
BadgerTables: Alpha.Conf.GetString("badger.tables"),
BadgerVlog: Alpha.Conf.GetString("badger.vlog"),
BadgerWalTables: Alpha.Conf.GetString("badger.wal_tables"),
BadgerWalVlog: Alpha.Conf.GetString("badger.wal_vlog"),
BadgerCompressionLevel: Alpha.Conf.GetInt("badger.compression_level"),
PostingDir: Alpha.Conf.GetString("postings"),
WALDir: Alpha.Conf.GetString("wal"),
Expand Down
9 changes: 7 additions & 2 deletions worker/config.go
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Expand Up @@ -39,10 +39,15 @@ const (
type Options struct {
// PostingDir is the path to the directory storing the postings..
PostingDir string
// BadgerTables is the name of the mode used to load the badger tables.
// BadgerTables is the name of the mode used to load the badger tables for the p directory.
BadgerTables string
// BadgerVlog is the name of the mode used to load the badger value log.
// BadgerVlog is the name of the mode used to load the badger value log for the p directory.
BadgerVlog string
// BadgerWalTables is the name of the mode used to load the badger tables for the w directory.
BadgerWalTables string
// BadgerWalVlog is the name of the mode used to load the badger value log for the w directory.
BadgerWalVlog string

// BadgerCompressionLevel is the ZSTD compression level used by badger. A
// higher value means more CPU intensive compression and better compression
// ratio.
Expand Down
29 changes: 17 additions & 12 deletions worker/server_state.go
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Expand Up @@ -62,7 +62,7 @@ func InitServerState() {
x.WorkerConfig.ProposedGroupId = groupId
}

func setBadgerOptions(opt badger.Options) badger.Options {
func setBadgerOptions(opt badger.Options, wal bool) badger.Options {
opt = opt.WithSyncWrites(false).
WithTruncate(true).
WithLogger(&x.ToGlog{}).
Expand All @@ -86,8 +86,20 @@ func setBadgerOptions(opt badger.Options) badger.Options {
opt.ZSTDCompressionLevel = Config.BadgerCompressionLevel
}

var badgerTables string
var badgerVlog string
if wal {
// Settings for the write-ahead log.
badgerTables = Config.BadgerWalTables
badgerVlog = Config.BadgerWalVlog
} else {
// Settings for the data directory.
badgerTables = Config.BadgerTables
badgerVlog = Config.BadgerVlog
}

glog.Infof("Setting Badger table load option: %s", Config.BadgerTables)
switch Config.BadgerTables {
switch badgerTables {
case "mmap":
opt.TableLoadingMode = options.MemoryMap
case "ram":
Expand All @@ -99,7 +111,7 @@ func setBadgerOptions(opt badger.Options) badger.Options {
}

glog.Infof("Setting Badger value log load option: %s", Config.BadgerVlog)
switch Config.BadgerVlog {
switch badgerVlog {
case "mmap":
opt.ValueLogLoadingMode = options.MemoryMap
case "disk":
Expand Down Expand Up @@ -128,17 +140,10 @@ func (s *ServerState) initStorage() {
// Write Ahead Log directory
x.Checkf(os.MkdirAll(Config.WALDir, 0700), "Error while creating WAL dir.")
opt := badger.LSMOnlyOptions(Config.WALDir)
opt = setBadgerOptions(opt)
opt = setBadgerOptions(opt, true)
opt.ValueLogMaxEntries = 10000 // Allow for easy space reclamation.
opt.MaxCacheSize = 10 << 20 // 10 mb of cache size for WAL.

// We should always force load LSM tables to memory, disregarding user settings, because
// Raft.Advance hits the WAL many times. If the tables are not in memory, retrieval slows
// down way too much, causing cluster membership issues. Because of prefix compression and
// value separation provided by Badger, this is still better than using the memory based WAL
// storage provided by the Raft library.
opt.TableLoadingMode = options.LoadToRAM

// Print the options w/o exposing key.
// TODO: Build a stringify interface in Badger options, which is used to print nicely here.
key := opt.EncryptionKey
Expand All @@ -161,7 +166,7 @@ func (s *ServerState) initStorage() {
WithKeepBlockIndicesInCache(true).
WithKeepBlocksInCache(true).
WithMaxBfCacheSize(500 << 20) // 500 MB of bloom filter cache.
opt = setBadgerOptions(opt)
opt = setBadgerOptions(opt, false)

// Print the options w/o exposing key.
// TODO: Build a stringify interface in Badger options, which is used to print nicely here.
Expand Down