Module API for Forking

* create module API for forking child processes.
* refactor duplicate code around creating and tracking forks by AOF and RDB.
* child processes listen to SIGUSR1 and dies exitFromChild in order to
  eliminate a valgrind warning of unhandled signal.
* note that BGSAVE error reply has changed.

valgrind error is:
  Process terminating with default action of signal 10 (SIGUSR1)
This commit is contained in:
Oran Agra
2019-07-17 08:51:02 +03:00
parent 4b2579a064
commit 56258c6b7d
15 changed files with 342 additions and 91 deletions

View File

@ -264,9 +264,9 @@ int startAppendOnly(void) {
strerror(errno));
return C_ERR;
}
if (server.rdb_child_pid != -1) {
if (hasForkChild() && server.aof_child_pid == -1) {
server.aof_rewrite_scheduled = 1;
serverLog(LL_WARNING,"AOF was enabled but there is already a child process saving an RDB file on disk. An AOF background was scheduled to start when possible.");
serverLog(LL_WARNING,"AOF was enabled but there is already another background operation. An AOF background was scheduled to start when possible.");
} else {
/* If there is a pending AOF rewrite, we need to switch it off and
* start a new one: the old one cannot be reused because it is not
@ -397,7 +397,7 @@ void flushAppendOnlyFile(int force) {
* useful for graphing / monitoring purposes. */
if (sync_in_progress) {
latencyAddSampleIfNeeded("aof-write-pending-fsync",latency);
} else if (server.aof_child_pid != -1 || server.rdb_child_pid != -1) {
} else if (hasForkChild()) {
latencyAddSampleIfNeeded("aof-write-active-child",latency);
} else {
latencyAddSampleIfNeeded("aof-write-alone",latency);
@ -493,9 +493,8 @@ void flushAppendOnlyFile(int force) {
try_fsync:
/* Don't fsync if no-appendfsync-on-rewrite is set to yes and there are
* children doing I/O in the background. */
if (server.aof_no_fsync_on_rewrite &&
(server.aof_child_pid != -1 || server.rdb_child_pid != -1))
return;
if (server.aof_no_fsync_on_rewrite && hasForkChild())
return;
/* Perform the fsync if needed. */
if (server.aof_fsync == AOF_FSYNC_ALWAYS) {
@ -1562,39 +1561,24 @@ void aofClosePipes(void) {
*/
int rewriteAppendOnlyFileBackground(void) {
pid_t childpid;
long long start;
if (server.aof_child_pid != -1 || server.rdb_child_pid != -1) return C_ERR;
if (hasForkChild()) return C_ERR;
if (aofCreatePipes() != C_OK) return C_ERR;
openChildInfoPipe();
start = ustime();
if ((childpid = fork()) == 0) {
if ((childpid = redisFork()) == 0) {
char tmpfile[256];
/* Child */
closeListeningSockets(0);
redisSetProcTitle("redis-aof-rewrite");
snprintf(tmpfile,256,"temp-rewriteaof-bg-%d.aof", (int) getpid());
if (rewriteAppendOnlyFile(tmpfile) == C_OK) {
size_t private_dirty = zmalloc_get_private_dirty(-1);
if (private_dirty) {
serverLog(LL_NOTICE,
"AOF rewrite: %zu MB of memory used by copy-on-write",
private_dirty/(1024*1024));
}
server.child_info_data.cow_size = private_dirty;
sendChildInfo(CHILD_INFO_TYPE_AOF);
sendChildCOWInfo(CHILD_INFO_TYPE_AOF, "AOF rewrite");
exitFromChild(0);
} else {
exitFromChild(1);
}
} else {
/* Parent */
server.stat_fork_time = ustime()-start;
server.stat_fork_rate = (double) zmalloc_used_memory() * 1000000 / server.stat_fork_time / (1024*1024*1024); /* GB per second. */
latencyAddSampleIfNeeded("fork",server.stat_fork_time/1000);
if (childpid == -1) {
closeChildInfoPipe();
serverLog(LL_WARNING,
@ -1608,7 +1592,6 @@ int rewriteAppendOnlyFileBackground(void) {
server.aof_rewrite_scheduled = 0;
server.aof_rewrite_time_start = time(NULL);
server.aof_child_pid = childpid;
updateDictResizePolicy();
/* We set appendseldb to -1 in order to force the next call to the
* feedAppendOnlyFile() to issue a SELECT command, so the differences
* accumulated by the parent into server.aof_rewrite_buf will start
@ -1623,7 +1606,7 @@ int rewriteAppendOnlyFileBackground(void) {
void bgrewriteaofCommand(client *c) {
if (server.aof_child_pid != -1) {
addReplyError(c,"Background append only file rewriting already in progress");
} else if (server.rdb_child_pid != -1) {
} else if (hasForkChild()) {
server.aof_rewrite_scheduled = 1;
addReplyStatus(c,"Background append only file rewriting scheduled");
} else if (rewriteAppendOnlyFileBackground() == C_OK) {