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blosc/blosc2.c: optimize the mutex lock with spin lock #1

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blosc/blosc2.c: optimize the mutex lock with spin lock #1

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27 changes: 14 additions & 13 deletions blosc/blosc2.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
#include <sys/types.h>
#include <assert.h>
#include <math.h>
#include <pthread.h>

#include "blosc2.h"
#include "blosc-private.h"
Expand Down Expand Up @@ -3055,10 +3056,10 @@ static void t_blosc_do_job(void *ctxt)
}
else {
// Use dynamic schedule via a queue. Get the next block.
pthread_mutex_lock(&context->count_mutex);
pthread_spin_lock(&context->count_spin);
context->thread_nblock++;
nblock_ = context->thread_nblock;
pthread_mutex_unlock(&context->count_mutex);
pthread_spin_unlock(&context->count_spin);
tblock = nblocks;
}

Expand Down Expand Up @@ -3119,15 +3120,15 @@ static void t_blosc_do_job(void *ctxt)
/* Check results for the compressed/decompressed block */
if (cbytes < 0) { /* compr/decompr failure */
/* Set giveup_code error */
pthread_mutex_lock(&context->count_mutex);
pthread_spin_lock(&context->count_spin);
context->thread_giveup_code = cbytes;
pthread_mutex_unlock(&context->count_mutex);
pthread_spin_unlock(&context->count_spin);
break;
}

if (compress && !memcpyed) {
/* Start critical section */
pthread_mutex_lock(&context->count_mutex);
pthread_spin_lock(&context->count_spin);
ntdest = context->output_bytes;
// Note: do not use a typical local dict_training variable here
// because it is probably cached from previous calls if the number of
Expand All @@ -3138,13 +3139,13 @@ static void t_blosc_do_job(void *ctxt)

if ((cbytes == 0) || (ntdest + cbytes > maxbytes)) {
context->thread_giveup_code = 0; /* incompressible buf */
pthread_mutex_unlock(&context->count_mutex);
pthread_spin_unlock(&context->count_spin);
break;
}
context->thread_nblock++;
nblock_ = context->thread_nblock;
context->output_bytes += cbytes;
pthread_mutex_unlock(&context->count_mutex);
pthread_spin_unlock(&context->count_spin);
/* End of critical section */

/* Copy the compressed buffer to destination */
Expand All @@ -3154,22 +3155,22 @@ static void t_blosc_do_job(void *ctxt)
nblock_++;
}
else {
pthread_mutex_lock(&context->count_mutex);
pthread_spin_lock(&context->count_spin);
context->thread_nblock++;
nblock_ = context->thread_nblock;
context->output_bytes += cbytes;
pthread_mutex_unlock(&context->count_mutex);
pthread_spin_unlock(&context->count_spin);
}

} /* closes while (nblock_) */

if (static_schedule) {
pthread_mutex_lock(&context->count_mutex);
pthread_spin_lock(&context->count_spin);
context->output_bytes = context->sourcesize;
if (compress) {
context->output_bytes += context->header_overhead;
}
pthread_mutex_unlock(&context->count_mutex);
pthread_spin_unlock(&context->count_spin);
}

}
Expand Down Expand Up @@ -3208,7 +3209,7 @@ int init_threadpool(blosc2_context *context) {
int rc2;

/* Initialize mutex and condition variable objects */
pthread_mutex_init(&context->count_mutex, NULL);
pthread_spin_init(&context->count_spin, PTHREAD_PROCESS_SHARED);
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@guowangy guowangy Oct 19, 2022

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PTHREAD_PROCESS_SHARED why we need this flag?

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@jiebinn jiebinn Oct 20, 2022

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PTHREAD_PROCESS_SHARED why we need this flag?

int pthread_spin_init(pthread_spinlock_t *lock, int pshared);

The pshared must be one of the following.
PTHREAD_PROCESS_PRIVATE/PTHREAD_PROCESS_SHARED
The 1st one has limited to the threads that are forked from the same process.
The 2nd one could be obtained by all the threads.

Reference Link: https://man7.org/linux/man-pages/man3/pthread_spin_init.3.html

pthread_mutex_init(&context->delta_mutex, NULL);
pthread_mutex_init(&context->nchunk_mutex, NULL);
pthread_cond_init(&context->delta_cv, NULL);
Expand Down Expand Up @@ -3613,7 +3614,7 @@ int release_threadpool(blosc2_context *context) {
}

/* Release mutex and condition variable objects */
pthread_mutex_destroy(&context->count_mutex);
pthread_spin_destroy(&context->count_spin);
pthread_mutex_destroy(&context->delta_mutex);
pthread_mutex_destroy(&context->nchunk_mutex);
pthread_cond_destroy(&context->delta_cv);
Expand Down
2 changes: 1 addition & 1 deletion blosc/context.h
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Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,7 @@ struct blosc2_context_s {
int16_t end_threads;
pthread_t *threads;
struct thread_context *thread_contexts; /* only for user-managed threads */
pthread_mutex_t count_mutex;
pthread_spinlock_t count_spin;
pthread_mutex_t nchunk_mutex;
#ifdef BLOSC_POSIX_BARRIERS
pthread_barrier_t barr_init;
Expand Down