From 784b93087c622999e225735c0c76d50241941022 Mon Sep 17 00:00:00 2001 From: antirez Date: Fri, 24 Aug 2012 19:28:44 +0200 Subject: [PATCH] Incrementally flush RDB on disk while loading it from a master. This fixes issue #539. Basically if there is enough free memory the OS may buffer the RDB file that the slave transfers on disk from the master. The file may actually be flused on disk at once by the operating system when it gets closed by Redis, causing the close system call to block for a long time. This patch is a modified version of one provided by yoav-steinberg of @garantiadata (the original version was posted in the issue #539 comments), and tries to flush the OS buffers incrementally (every 8 MB of loaded data). --- src/config.h | 8 ++++++++ src/fmacros.h | 4 ++++ src/redis.c | 5 +++-- src/redis.h | 4 +++- src/replication.c | 36 +++++++++++++++++++++++++++--------- 5 files changed, 45 insertions(+), 12 deletions(-) diff --git a/src/config.h b/src/config.h index 28ef37d6..617682fc 100644 --- a/src/config.h +++ b/src/config.h @@ -52,6 +52,14 @@ #define aof_fsync fsync #endif +/* Define rdb_fsync_range to sync_file_range() on Linux, otherwise we use + * the plain fsync() call. */ +#ifdef __linux__ +#define rdb_fsync_range(fd,off,size) sync_file_range(fd,off,size,SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE) +#else +#define rdb_fsync_range(fd,off,size) fsync(fd) +#endif + /* Byte ordering detection */ #include /* This will likely define BYTE_ORDER */ diff --git a/src/fmacros.h b/src/fmacros.h index 866a9afa..3e548765 100644 --- a/src/fmacros.h +++ b/src/fmacros.h @@ -3,6 +3,10 @@ #define _BSD_SOURCE +#if defined(__linux__) +#define _GNU_SOURCE +#endif + #if defined(__linux__) || defined(__OpenBSD__) #define _XOPEN_SOURCE 700 #else diff --git a/src/redis.c b/src/redis.c index 92f1323b..0d7432d2 100644 --- a/src/redis.c +++ b/src/redis.c @@ -2079,9 +2079,10 @@ sds genRedisInfoString(char *section) { if (server.repl_state == REDIS_REPL_TRANSFER) { info = sdscatprintf(info, - "master_sync_left_bytes:%ld\r\n" + "master_sync_left_bytes:%lld\r\n" "master_sync_last_io_seconds_ago:%d\r\n" - ,(long)server.repl_transfer_left, + , (long long) + (server.repl_transfer_size - server.repl_transfer_read), (int)(server.unixtime-server.repl_transfer_lastio) ); } diff --git a/src/redis.h b/src/redis.h index d12e9445..52bf5b8d 100644 --- a/src/redis.h +++ b/src/redis.h @@ -684,7 +684,9 @@ struct redisServer { redisClient *master; /* Client that is master for this slave */ int repl_syncio_timeout; /* Timeout for synchronous I/O calls */ int repl_state; /* Replication status if the instance is a slave */ - off_t repl_transfer_left; /* Bytes left reading .rdb */ + off_t repl_transfer_size; /* Size of RDB to read from master during sync. */ + off_t repl_transfer_read; /* Amount of RDB read from master during sync. */ + off_t repl_transfer_last_fsync_off; /* Offset when we fsync-ed last time. */ int repl_transfer_s; /* Slave -> Master SYNC socket */ int repl_transfer_fd; /* Slave -> Master SYNC temp file descriptor */ char *repl_transfer_tmpfile; /* Slave-> master SYNC temp file name */ diff --git a/src/replication.c b/src/replication.c index 45a223b8..543477b6 100644 --- a/src/replication.c +++ b/src/replication.c @@ -311,16 +311,18 @@ void replicationAbortSyncTransfer(void) { } /* Asynchronously read the SYNC payload we receive from a master */ +#define REPL_MAX_WRITTEN_BEFORE_FSYNC (1024*1024*8) /* 8 MB */ void readSyncBulkPayload(aeEventLoop *el, int fd, void *privdata, int mask) { char buf[4096]; ssize_t nread, readlen; + off_t left; REDIS_NOTUSED(el); REDIS_NOTUSED(privdata); REDIS_NOTUSED(mask); - /* If repl_transfer_left == -1 we still have to read the bulk length + /* If repl_transfer_size == -1 we still have to read the bulk length * from the master reply. */ - if (server.repl_transfer_left == -1) { + if (server.repl_transfer_size == -1) { if (syncReadLine(fd,buf,1024,server.repl_syncio_timeout*1000) == -1) { redisLog(REDIS_WARNING, "I/O error reading bulk count from MASTER: %s", @@ -343,16 +345,16 @@ void readSyncBulkPayload(aeEventLoop *el, int fd, void *privdata, int mask) { redisLog(REDIS_WARNING,"Bad protocol from MASTER, the first byte is not '$', are you sure the host and port are right?"); goto error; } - server.repl_transfer_left = strtol(buf+1,NULL,10); + server.repl_transfer_size = strtol(buf+1,NULL,10); redisLog(REDIS_NOTICE, "MASTER <-> SLAVE sync: receiving %ld bytes from master", - server.repl_transfer_left); + server.repl_transfer_size); return; } /* Read bulk data */ - readlen = (server.repl_transfer_left < (signed)sizeof(buf)) ? - server.repl_transfer_left : (signed)sizeof(buf); + left = server.repl_transfer_size - server.repl_transfer_read; + readlen = (left < (signed)sizeof(buf)) ? left : (signed)sizeof(buf); nread = read(fd,buf,readlen); if (nread <= 0) { redisLog(REDIS_WARNING,"I/O error trying to sync with MASTER: %s", @@ -365,9 +367,23 @@ void readSyncBulkPayload(aeEventLoop *el, int fd, void *privdata, int mask) { redisLog(REDIS_WARNING,"Write error or short write writing to the DB dump file needed for MASTER <-> SLAVE synchronization: %s", strerror(errno)); goto error; } - server.repl_transfer_left -= nread; + server.repl_transfer_read += nread; + + /* Sync data on disk from time to time, otherwise at the end of the transfer + * we may suffer a big delay as the memory buffers are copied into the + * actual disk. */ + if (server.repl_transfer_read >= + server.repl_transfer_last_fsync_off + REPL_MAX_WRITTEN_BEFORE_FSYNC) + { + off_t sync_size = server.repl_transfer_read - + server.repl_transfer_last_fsync_off; + rdb_fsync_range(server.repl_transfer_fd, + server.repl_transfer_last_fsync_off, sync_size); + server.repl_transfer_last_fsync_off += sync_size; + } + /* Check if the transfer is now complete */ - if (server.repl_transfer_left == 0) { + if (server.repl_transfer_read == server.repl_transfer_size) { if (rename(server.repl_transfer_tmpfile,server.rdb_filename) == -1) { redisLog(REDIS_WARNING,"Failed trying to rename the temp DB into dump.rdb in MASTER <-> SLAVE synchronization: %s", strerror(errno)); replicationAbortSyncTransfer(); @@ -538,7 +554,9 @@ void syncWithMaster(aeEventLoop *el, int fd, void *privdata, int mask) { } server.repl_state = REDIS_REPL_TRANSFER; - server.repl_transfer_left = -1; + server.repl_transfer_size = -1; + server.repl_transfer_read = 0; + server.repl_transfer_last_fsync_off = 0; server.repl_transfer_fd = dfd; server.repl_transfer_lastio = server.unixtime; server.repl_transfer_tmpfile = zstrdup(tmpfile); -- 2.45.2