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Ensure that on EAGAIN we continue to try to spawn a worker. When workers finish with a queue have them migrate to the other queues looking for work.

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This commit is contained in:
Gregory Burd 2013-07-25 13:29:16 -04:00
parent 122963133a
commit 3627ff8690
3 changed files with 42 additions and 23 deletions
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55
c_src/async_nif.h
View file

@ -37,6 +37,7 @@ extern "C" {
#define ASYNC_NIF_WORKER_QUEUE_SIZE 100
#define ASYNC_NIF_MAX_QUEUED_REQS ASYNC_NIF_WORKER_QUEUE_SIZE * ASYNC_NIF_MAX_WORKERS
struct async_nif_req_entry {
ERL_NIF_TERM ref;
ErlNifEnv *env;
@ -53,6 +54,7 @@ struct async_nif_work_queue {
unsigned int depth;
ErlNifMutex *reqs_mutex;
ErlNifCond *reqs_cnd;
struct async_nif_work_queue *next;
STAILQ_HEAD(reqs, async_nif_req_entry) reqs;
};
@ -148,14 +150,14 @@ struct async_nif_state {
#define ASYNC_NIF_LOAD(name, priv) do { \
if (!name##_async_nif_coord) \
name##_async_nif_coord = enif_mutex_create(NULL); \
name##_async_nif_coord = enif_mutex_create("nif_coord load"); \
enif_mutex_lock(name##_async_nif_coord); \
priv = async_nif_load(); \
enif_mutex_unlock(name##_async_nif_coord); \
} while(0);
#define ASYNC_NIF_UNLOAD(name, env, priv) do { \
if (!name##_async_nif_coord) \
name##_async_nif_coord = enif_mutex_create(NULL); \
name##_async_nif_coord = enif_mutex_create("nif_coord unload"); \
enif_mutex_lock(name##_async_nif_coord); \
async_nif_unload(env, priv); \
enif_mutex_unlock(name##_async_nif_coord); \
@ -164,7 +166,7 @@ struct async_nif_state {
} while(0);
#define ASYNC_NIF_UPGRADE(name, env) do { \
if (!name##_async_nif_coord) \
name##_async_nif_coord = enif_mutex_create(NULL); \
name##_async_nif_coord = enif_mutex_create("nif_coord upgrade"); \
enif_mutex_lock(name##_async_nif_coord); \
async_nif_upgrade(env); \
enif_mutex_unlock(name##_async_nif_coord); \
@ -197,7 +199,7 @@ async_nif_reuse_req(struct async_nif_state *async_nif)
env = enif_alloc_env();
if (env) {
req->env = env;
async_nif->num_reqs++;
__sync_fetch_and_add(&async_nif->num_reqs, 1);
} else {
enif_free(req);
req = NULL;
@ -287,7 +289,7 @@ static ERL_NIF_TERM
async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_entry *req, int hint)
{
/* Identify the most appropriate worker for this request. */
unsigned int i, qid = 0;
unsigned int i, last_qid, qid = 0;
struct async_nif_work_queue *q = NULL;
double avg_depth;
@ -297,9 +299,10 @@ async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_en
if (hint >= 0) {
qid = (unsigned int)hint;
} else {
qid = async_nif->next_q;
qid = (qid + 1) % async_nif->num_queues;
async_nif->next_q = qid;
do {
last_qid = __sync_fetch_and_add(&async_nif->next_q, 0);
qid = (last_qid + 1) % async_nif->num_queues;
} while (!__sync_bool_compare_and_swap(&async_nif->next_q, last_qid, qid));
}
/* Now we inspect and interate across the set of queues trying to select one
@ -343,12 +346,19 @@ async_nif_enqueue_req(struct async_nif_state* async_nif, struct async_nif_req_en
/* Add the request to the queue. */
STAILQ_INSERT_TAIL(&q->reqs, req, entries);
q->depth++;
__sync_fetch_and_add(&q->depth, 1);
/* We've selected a queue for this new request now check to make sure there are
enough workers actively processing requests on this queue. */
if (q->depth > q->num_workers || q->num_workers == 0)
if (async_nif_start_worker(async_nif, q) == 0) q->num_workers++;
retry:
if (q->depth > q->num_workers || q->num_workers == 0) {
switch(async_nif_start_worker(async_nif, q)) {
case 0: __sync_fetch_and_add(&q->num_workers, 1); break;
case EAGAIN: goto retry;
case EINVAL: case ENOMEM: default: return 0;
}
}
/* Build the term before releasing the lock so as not to race on the use of
the req pointer (which will soon become invalid in another thread
@ -373,6 +383,7 @@ async_nif_worker_fn(void *arg)
struct async_nif_state *async_nif = we->async_nif;
struct async_nif_work_queue *q = we->q;
struct async_nif_req_entry *req = NULL;
unsigned int tries = async_nif->num_queues;
for(;;) {
/* Examine the request queue, are there things to be done? */
@ -386,7 +397,14 @@ async_nif_worker_fn(void *arg)
/* Queue is empty so we wait for more work to arrive. */
if (q->num_workers > ASYNC_NIF_MIN_WORKERS) {
enif_mutex_unlock(q->reqs_mutex);
break;
if (tries == 0 && q == we->q) break; // we've tried all queues, thread exit
else {
tries--;
__sync_fetch_and_add(&q->num_workers, -1);
q = q->next;
__sync_fetch_and_add(&q->num_workers, 1);
continue; // try another queue
}
} else {
enif_cond_wait(q->reqs_cnd, q->reqs_mutex);
goto check_again_for_work;
@ -396,7 +414,7 @@ async_nif_worker_fn(void *arg)
reqs_mutex lock. Take the request off the queue. */
req = STAILQ_FIRST(&q->reqs);
STAILQ_REMOVE(&q->reqs, req, async_nif_req_entry, entries);
q->depth--;
__sync_fetch_and_add(&q->depth, -1);
/* Ensure that there is at least one other worker thread watching this
queue. */
@ -422,7 +440,7 @@ async_nif_worker_fn(void *arg)
enif_mutex_lock(async_nif->we_mutex);
SLIST_INSERT_HEAD(&async_nif->we_joining, we, entries);
enif_mutex_unlock(async_nif->we_mutex);
q->num_workers--;
__sync_fetch_and_add(&q->num_workers, -1);
enif_thread_exit(0);
return 0;
}
@ -554,15 +572,16 @@ async_nif_load()
async_nif->next_q = 0;
async_nif->shutdown = 0;
STAILQ_INIT(&async_nif->recycled_reqs);
async_nif->recycled_req_mutex = enif_mutex_create(NULL);
async_nif->we_mutex = enif_mutex_create(NULL);
async_nif->recycled_req_mutex = enif_mutex_create("recycled_req");
async_nif->we_mutex = enif_mutex_create("we");
SLIST_INIT(&async_nif->we_joining);
for (i = 0; i < async_nif->num_queues; i++) {
struct async_nif_work_queue *q = &async_nif->queues[i];
STAILQ_INIT(&q->reqs);
q->reqs_mutex = enif_mutex_create(NULL);
q->reqs_cnd = enif_cond_create(NULL);
q->reqs_mutex = enif_mutex_create("reqs");
q->reqs_cnd = enif_cond_create("reqs");
q->next = &async_nif->queues[(i + 1) % num_queues];
}
return async_nif;
}

2
c_src/build_deps.sh
View file

@ -58,7 +58,7 @@ get_wt ()
wt_configure ()
{
(cd $BASEDIR/$WT_DIR/build_posix
../configure --with-pic \
CFLAGS+=-g ../configure --with-pic \
--enable-snappy \
--prefix=${BASEDIR}/system || exit 1)
}

8
c_src/wterl.c
View file

@ -648,7 +648,7 @@ ASYNC_NIF_DECL(
} else {
conn_handle->session_config = NULL;
}
conn_handle->cache_mutex = enif_mutex_create(NULL);
conn_handle->cache_mutex = enif_mutex_create("conn_handle");
enif_mutex_lock(conn_handle->cache_mutex);
conn_handle->conn = conn;
ERL_NIF_TERM result = enif_make_resource(env, conn_handle);
@ -2259,9 +2259,9 @@ on_load(ErlNifEnv *env, void **priv_data, ERL_NIF_TERM load_info)
memset(priv, 0, sizeof(struct wterl_priv_data));
struct wterl_event_handlers *eh = &priv->eh;
eh->error_mutex = enif_mutex_create(NULL);
eh->message_mutex = enif_mutex_create(NULL);
eh->progress_mutex = enif_mutex_create(NULL);
eh->error_mutex = enif_mutex_create("error_mutex");
eh->message_mutex = enif_mutex_create("message_mutex");
eh->progress_mutex = enif_mutex_create("progress_mutex");
/* Process the load_info array of tuples, we expect:
[{wterl_vsn, "a version string"},