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Reuse threads by using GLib's threadpool

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This commit is contained in:
Kleis Auke Wolthuizen 2021-03-18 16:53:00 +01:00
parent 1423c550cc
commit 80e0cc3d12
4 changed files with 270 additions and 277 deletions
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1
libvips/include/vips/internal.h
View File

@ -111,6 +111,7 @@ extern gboolean vips__cache_trace;
extern int vips__n_active_threads;
void vips__threadpool_init( void );
void vips__threadpool_shutdown( void );
void vips__cache_init( void );

3
libvips/include/vips/threadpool.h
View File

@ -5,6 +5,8 @@
* 17/3/10
* - from threadgroup
* - rework with a simpler distributed work allocation model
* 02/02/20 kleisauke
* - reuse threads by using GLib's threadpool
*/
/*
@ -130,6 +132,7 @@ typedef int (*VipsThreadpoolWorkFn)( VipsThreadState *state, void *a );
*/
typedef int (*VipsThreadpoolProgressFn)( void *a );
int vips_threadpool_push( const char *name, GFunc func, gpointer data );
int vips_threadpool_run( VipsImage *im,
VipsThreadStartFn start,
VipsThreadpoolAllocateFn allocate,

4
libvips/iofuncs/init.c
View File

@ -665,7 +665,7 @@ vips_leak( void )
*
* This function needs to be called when a thread that has been using vips
* exits. It is called for you by vips_shutdown() and for any threads created
* by vips_g_thread_new().
* within the #VipsThreadPool.
*
* You will need to call it from threads created in
* other ways or there will be memory leaks. If you do not call it, vips
@ -719,6 +719,8 @@ vips_shutdown( void )
vips__thread_profile_stop();
vips__threadpool_shutdown();
#ifdef HAVE_GSF
gsf_shutdown();
#endif /*HAVE_GSF*/

539
libvips/iofuncs/threadpool.c
View File

@ -23,6 +23,8 @@
* - don't depend on image width when setting n_lines
* 27/2/19 jtorresfabra
* - free threadpool earlier
* 02/02/20 kleisauke
* - reuse threads by using GLib's threadpool
*/
/*
@ -87,6 +89,15 @@
* @include: vips/vips.h
* @title: VipsThreadpool
*
* A threadpool which allows reusing already started threads. Implementing
* this can be tedious and error-prone. Therefore we use the GLib
* provided threadpool for our convenience. An added advantage is, that
* the threads can be shared between the different subsystems, when they
* are using GLib.
*
* The threadpool is created during vips_init() and is destroyed by
* vips_shutdown().
*
* vips_threadpool_run() loops a set of threads over an image. Threads take it
* in turns to allocate units of work (a unit might be a tile in an image),
* then run in parallel to process those units. An optional progress function
@ -121,6 +132,10 @@ static GPrivate *is_worker_key = NULL;
*/
static gboolean vips__stall = FALSE;
/* The thread pool we'll use.
*/
static GThreadPool *vips__pool = NULL;
/* Glib 2.32 revised the thread API. We need some compat functions.
*/
@ -273,23 +288,38 @@ vips_g_thread_join( GThread *thread )
return( result );
}
/**
* vips_concurrency_set:
* @concurrency: number of threads to run
*
* Sets the number of worker threads that vips should use when running a
* #VipsThreadPool.
*
* The special value 0 means "default". In this case, the number of threads is
* set by the environment variable VIPS_CONCURRENCY, or if that is not set, the
* number of threads availble on the host machine.
*
* See also: vips_concurrency_get().
*/
void
vips_concurrency_set( int concurrency )
typedef struct {
/* An name for this thread.
*/
const char *name;
/* The function to execute within the #VipsThreadPool.
*/
GFunc func;
/* User data that is handed over to func when it is called.
*/
gpointer data;
} VipsThreadExec;
static void
vips_thread_main_loop( gpointer thread_data, gpointer pool_data )
{
vips__concurrency = concurrency;
VipsThreadExec *exec = (VipsThreadExec *) thread_data;
/* Set this to something (anything) to tag this thread as a vips
* worker.
*/
g_private_set( is_worker_key, thread_data );
if( vips__thread_profile )
vips__thread_profile_attach( exec->name );
exec->func( exec->data, pool_data );
g_free( exec );
vips_thread_shutdown();
}
static int
@ -371,6 +401,67 @@ get_num_processors( void )
#endif /*!GLIB_CHECK_VERSION( 2, 48, 1 )*/
}
/* The default concurrency, set by the environment variable VIPS_CONCURRENCY,
* or if that is not set, the number of threads available on the host machine.
*/
static int
vips__concurrency_get_default( void )
{
const char *str;
int nthr;
int x;
/* Tell the threads system how much concurrency we expect.
*/
if( vips__concurrency > 0 )
nthr = vips__concurrency;
else if( ((str = g_getenv( "VIPS_CONCURRENCY" ))
#if ENABLE_DEPRECATED
|| (str = g_getenv( "IM_CONCURRENCY" ))
#endif
) && (x = atoi( str )) > 0 )
nthr = x;
else
nthr = get_num_processors();
if( nthr < 1 || nthr > MAX_THREADS ) {
nthr = VIPS_CLIP( 1, nthr, MAX_THREADS );
g_warning( _( "threads clipped to %d" ), nthr );
}
return nthr;
}
/**
* vips_concurrency_set:
* @concurrency: number of threads to run
*
* Sets the number of worker threads that vips should use when running a
* #VipsThreadPool.
*
* The special value 0 means "default". In this case, the number of threads is
* set by the environment variable VIPS_CONCURRENCY, or if that is not set, the
* number of threads available on the host machine.
*
* See also: vips_concurrency_get().
*/
void
vips_concurrency_set( int concurrency )
{
/* Tell the threads system how much concurrency we expect.
*/
if( concurrency < 1 )
concurrency = vips__concurrency_get_default();
else if( concurrency > MAX_THREADS ) {
concurrency = MAX_THREADS;
g_warning( _( "threads clipped to %d" ), MAX_THREADS );
}
vips__concurrency = concurrency;
}
/**
* vips_concurrency_get:
*
@ -398,34 +489,7 @@ get_num_processors( void )
int
vips_concurrency_get( void )
{
const char *str;
int nthr;
int x;
/* Tell the threads system how much concurrency we expect.
*/
if( vips__concurrency > 0 )
nthr = vips__concurrency;
else if( ((str = g_getenv( "VIPS_CONCURRENCY" ))
#if ENABLE_DEPRECATED
|| (str = g_getenv( "IM_CONCURRENCY" ))
#endif
) && (x = atoi( str )) > 0 )
nthr = x;
else
nthr = get_num_processors();
if( nthr < 1 || nthr > MAX_THREADS ) {
nthr = VIPS_CLIP( 1, nthr, MAX_THREADS );
g_warning( _( "threads clipped to %d" ), nthr );
}
/* Save for next time around.
*/
vips_concurrency_set( nthr );
return( nthr );
return( vips__concurrency );
}
G_DEFINE_TYPE( VipsThreadState, vips_thread_state, VIPS_TYPE_OBJECT );
@ -500,41 +564,17 @@ vips_thread_state_new( VipsImage *im, void *a )
VIPS_TYPE_THREAD_STATE, vips_thread_state_set, im, a ) ) );
}
/* What we track for each thread in the pool.
/* What we track for a task within the #VipsThreadPool.
*/
typedef struct {
/* All private.
*/
/*< private >*/
struct _VipsThreadpool *pool; /* Pool we are part of */
VipsThreadState *state;
/* Thread we are running.
*/
GThread *thread;
/* Set this to ask the thread to exit.
*/
gboolean exit;
/* Set by the thread if work or allocate return an error.
*/
gboolean error;
} VipsThread;
/* What we track for a group of threads working together.
*/
typedef struct _VipsThreadpool {
typedef struct _VipsTask {
/* All private.
*/
/*< private >*/
VipsImage *im; /* Image we are calculating */
/* Start a thread, do a unit of work (runs in parallel) and allocate
* a unit of work (serial). Plus the mutex we use to serialize work
* allocation.
/* Start or reuse a thread, do a unit of work (runs in parallel)
* and allocate a unit of work (serial). Plus the mutex we use to
* serialize work allocation.
*/
VipsThreadStartFn start;
VipsThreadpoolAllocateFn allocate;
@ -542,10 +582,7 @@ typedef struct _VipsThreadpool {
GMutex *allocate_lock;
void *a; /* User argument to start / allocate / etc. */
int nthr; /* Number of threads in pool */
VipsThread **thr; /* Threads */
/* The caller blocks here until all threads finish.
/* The caller blocks here until all tasks finish.
*/
VipsSemaphore finish;
@ -560,46 +597,7 @@ typedef struct _VipsThreadpool {
/* Set by Allocate (via an arg) to indicate normal end of computation.
*/
gboolean stop;
} VipsThreadpool;
/* Junk a thread.
*/
static void
vips_thread_free( VipsThread *thr )
{
/* Is there a thread running this region? Kill it!
*/
if( thr->thread ) {
thr->exit = 1;
/* Return value is always NULL (see thread_main_loop).
*/
(void) vips_g_thread_join( thr->thread );
thr->thread = NULL;
}
VIPS_FREEF( g_object_unref, thr->state );
thr->pool = NULL;
VIPS_FREE( thr );
}
static int
vips_thread_allocate( VipsThread *thr )
{
VipsThreadpool *pool = thr->pool;
g_assert( !pool->stop );
if( !thr->state &&
!(thr->state = pool->start( pool->im, pool->a )) )
return( -1 );
if( pool->allocate( thr->state, pool->a, &pool->stop ) )
return( -1 );
return( 0 );
}
} VipsTask;
/* Run this once per main loop. Get some work (single-threaded), then do it
* (many-threaded).
@ -608,221 +606,203 @@ vips_thread_allocate( VipsThread *thr )
* loaders a change to seek to the correct spot, see vips_sequential().
*/
static void
vips_thread_work_unit( VipsThread *thr )
vips_task_work_unit( VipsTask *task, VipsThreadState *state )
{
VipsThreadpool *pool = thr->pool;
if( thr->error )
if( task->error )
return;
VIPS_GATE_START( "vips_thread_work_unit: wait" );
VIPS_GATE_START( "vips_task_work_unit: wait" );
g_mutex_lock( pool->allocate_lock );
g_mutex_lock( task->allocate_lock );
VIPS_GATE_STOP( "vips_thread_work_unit: wait" );
VIPS_GATE_STOP( "vips_task_work_unit: wait" );
/* Has another worker signaled stop while we've been working?
*/
if( pool->stop ) {
g_mutex_unlock( pool->allocate_lock );
if( task->stop ) {
g_mutex_unlock( task->allocate_lock );
return;
}
if( vips_thread_allocate( thr ) ) {
thr->error = TRUE;
pool->error = TRUE;
g_mutex_unlock( pool->allocate_lock );
if( task->allocate( state, task->a, &task->stop ) ) {
task->error = TRUE;
g_mutex_unlock( task->allocate_lock );
return;
}
/* Have we just signalled stop?
*/
if( pool->stop ) {
g_mutex_unlock( pool->allocate_lock );
if( task->stop ) {
g_mutex_unlock( task->allocate_lock );
return;
}
g_mutex_unlock( pool->allocate_lock );
g_mutex_unlock( task->allocate_lock );
if( thr->state->stall &&
if( state->stall &&
vips__stall ) {
/* Sleep for 0.5s. Handy for stressing the seq system. Stall
* is set by allocate funcs in various places.
*/
g_usleep( 500000 );
thr->state->stall = FALSE;
printf( "vips_thread_work_unit: "
"stall done, releasing y = %d ...\n", thr->state->y );
state->stall = FALSE;
printf( "vips_task_work_unit: "
"stall done, releasing y = %d ...\n", state->y );
}
/* Process a work unit.
*/
if( pool->work( thr->state, pool->a ) ) {
thr->error = TRUE;
pool->error = TRUE;
}
if( task->work( state, task->a ) )
task->error = TRUE;
}
/* What runs as a thread ... loop, waiting to be told to do stuff.
*/
static void *
vips_thread_main_loop( void *a )
static void
vips_task_run( gpointer data, gpointer user_data )
{
VipsThread *thr = (VipsThread *) a;
VipsThreadpool *pool = thr->pool;
VipsTask *task = (VipsTask *) data;
VipsThreadState *state;
g_assert( pool == thr->pool );
VIPS_GATE_START( "vips_task_run: thread" );
VIPS_GATE_START( "vips_thread_main_loop: thread" );
// TODO: Could we move this to vips_task_work_unit()?
g_mutex_lock( task->allocate_lock );
if( !(state = task->start( task->im, task->a )) )
task->error = TRUE;
g_mutex_unlock( task->allocate_lock );
/* Process work units! Always tick, even if we are stopping, so the
* main thread will wake up for exit.
*/
for(;;) {
VIPS_GATE_START( "vips_thread_work_unit: u" );
vips_thread_work_unit( thr );
VIPS_GATE_STOP( "vips_thread_work_unit: u" );
vips_semaphore_up( &pool->tick );
VIPS_GATE_START( "vips_task_work_unit: u" );
vips_task_work_unit( task, state );
VIPS_GATE_STOP( "vips_task_work_unit: u" );
vips_semaphore_up( &task->tick );
if( pool->stop ||
pool->error )
if( task->stop ||
task->error )
break;
}
g_mutex_lock( task->allocate_lock );
VIPS_FREEF( g_object_unref, state );
g_mutex_unlock( task->allocate_lock );
/* We are exiting: tell the main thread.
*/
vips_semaphore_up( &pool->finish );
vips_semaphore_up( &task->finish );
VIPS_GATE_STOP( "vips_thread_main_loop: thread" );
return( NULL );
VIPS_GATE_STOP( "vips_task_run: thread" );
}
/* Attach another thread to a threadpool.
/* Called from vips_shutdown().
*/
static VipsThread *
vips_thread_new( VipsThreadpool *pool )
void
vips__threadpool_shutdown( void )
{
VipsThread *thr;
if( !(thr = VIPS_NEW( NULL, VipsThread )) )
return( NULL );
thr->pool = pool;
thr->state = NULL;
thr->thread = NULL;
thr->exit = 0;
thr->error = 0;
/* We can't build the state here, it has to be done by the worker
* itself the first time that allocate runs so that any regions are
* owned by the correct thread.
/* We may come here without having inited.
*/
if( vips__pool ) {
VIPS_DEBUG_MSG( "vips__threadpool_shutdown: (%p)\n", vips__pool );
if( !(thr->thread = vips_g_thread_new( "worker",
vips_thread_main_loop, thr )) ) {
vips_thread_free( thr );
return( NULL );
}
return( thr );
}
/* Kill all threads in a threadpool, if there are any. Can be called multiple
* times.
*/
static void
vips_threadpool_kill_threads( VipsThreadpool *pool )
{
if( pool->thr ) {
int i;
for( i = 0; i < pool->nthr; i++ )
VIPS_FREEF( vips_thread_free, pool->thr[i] );
VIPS_DEBUG_MSG( "vips_threadpool_kill_threads: "
"killed %d threads\n", pool->nthr );
g_thread_pool_free( vips__pool, TRUE, TRUE );
vips__pool = NULL;
}
}
static void
vips_threadpool_free( VipsThreadpool *pool )
static VipsTask *
vips_task_new( VipsImage *im, int *n_tasks )
{
VIPS_DEBUG_MSG( "vips_threadpool_free: \"%s\" (%p)\n",
pool->im->filename, pool );
vips_threadpool_kill_threads( pool );
VIPS_FREEF( vips_g_mutex_free, pool->allocate_lock );
vips_semaphore_destroy( &pool->finish );
vips_semaphore_destroy( &pool->tick );
VIPS_FREE( pool->thr );
VIPS_FREE( pool );
}
static VipsThreadpool *
vips_threadpool_new( VipsImage *im )
{
VipsThreadpool *pool;
VipsTask *task;
int tile_width;
int tile_height;
gint64 n_tiles;
int n_lines;
/* Allocate and init new thread block.
/* Allocate and init a new task.
*/
if( !(pool = VIPS_NEW( NULL, VipsThreadpool )) )
if( !(task = VIPS_NEW( NULL, VipsTask )) )
return( NULL );
pool->im = im;
pool->allocate = NULL;
pool->work = NULL;
pool->allocate_lock = vips_g_mutex_new();
pool->nthr = vips_concurrency_get();
pool->thr = NULL;
vips_semaphore_init( &pool->finish, 0, "finish" );
vips_semaphore_init( &pool->tick, 0, "tick" );
pool->error = FALSE;
pool->stop = FALSE;
task->im = im;
task->allocate = NULL;
task->work = NULL;
task->allocate_lock = vips_g_mutex_new();
vips_semaphore_init( &task->finish, 0, "finish" );
vips_semaphore_init( &task->tick, 0, "tick" );
task->error = FALSE;
task->stop = FALSE;
/* If this is a tiny image, we won't need all nthr threads. Guess how
*n_tasks = vips_concurrency_get();
/* If this is a tiny image, we won't need all n_tasks. Guess how
* many tiles we might need to cover the image and use that to limit
* the number of threads we create.
* the number of tasks we create.
*/
vips_get_tile_size( im, &tile_width, &tile_height, &n_lines );
n_tiles = (1 + (gint64) im->Xsize / tile_width) *
(1 + (gint64) im->Ysize / tile_height);
n_tiles = VIPS_CLIP( 0, n_tiles, MAX_THREADS );
pool->nthr = VIPS_MIN( pool->nthr, n_tiles );
n_tiles = VIPS_MAX( 0, n_tiles );
*n_tasks = VIPS_MIN( *n_tasks, n_tiles );
VIPS_DEBUG_MSG( "vips_threadpool_new: \"%s\" (%p), with %d threads\n",
im->filename, pool, pool->nthr );
VIPS_DEBUG_MSG( "vips_task_new: \"%s\" (%p), with %d tasks\n",
im->filename, task, *n_tasks );
return( pool );
return( task );
}
/* Attach a set of threads.
*/
static int
vips_threadpool_create_threads( VipsThreadpool *pool )
static void
vips_task_free( VipsTask *task )
{
int i;
VIPS_DEBUG_MSG( "vips_task_free: \"%s\" (%p)\n",
task->im->filename, task );
g_assert( !pool->thr );
VIPS_FREEF( vips_g_mutex_free, task->allocate_lock );
vips_semaphore_destroy( &task->finish );
vips_semaphore_destroy( &task->tick );
VIPS_FREE( task );
}
/* Make thread array.
*/
if( !(pool->thr = VIPS_ARRAY( NULL, pool->nthr, VipsThread * )) )
/**
* vips_threadpool_push.
* @name an name for the thread
* @func a function to execute in the thread pool
* @data an argument to supply to @func
*
* Inserts a new function into the list of tasks to be executed by the
* #VipsThreadPool. A newly created or reused thread will execute
* @func with with the argument data.
*
* When the number of currently running threads is lower than the
* maximal allowed number of threads set by vips_concurrency_set(),
* a new thread is started (or reused).
* Otherwise, it stays in the queue until a thread in this pool
* finishes its previous task and processes the @func.
*
* See also: vips_concurrency_set().
*
* Returns: 0 on success, -1 on error.
*/
int
vips_threadpool_push( const char *name, GFunc func, gpointer data )
{
VipsThreadExec *exec;
GError *error = NULL;
gboolean result;
exec = g_new( VipsThreadExec, 1 );
exec->name = name;
exec->func = func;
exec->data = data;
result = g_thread_pool_push( vips__pool, exec, &error );
if( error ) {
vips_g_error( &error );
return( -1 );
for( i = 0; i < pool->nthr; i++ )
pool->thr[i] = NULL;
}
/* Attach threads and start them working.
*/
for( i = 0; i < pool->nthr; i++ )
if( !(pool->thr[i] = vips_thread_new( pool )) ) {
vips_threadpool_kill_threads( pool );
return( -1 );
}
return( 0 );
return( result ? 0 : -1 );
}
/**
@ -908,7 +888,8 @@ vips_threadpool_create_threads( VipsThreadpool *pool )
* @progress: give progress feedback about a work unit, or %NULL
* @a: client data
*
* This function runs a set of threads over an image. Each thread first calls
* This function runs a set of threads over an image. It will use a newly
* created or reused thread within the #VipsThreadPool. Each thread first calls
* @start to create new per-thread state, then runs
* @allocate to set up a new work unit (perhaps the next tile in an image, for
* example), then @work to process that work unit. After each unit is
@ -935,60 +916,61 @@ vips_threadpool_run( VipsImage *im,
VipsThreadpoolProgressFn progress,
void *a )
{
VipsThreadpool *pool;
VipsTask *task;
int n_tasks;
int i;
int result;
if( !(pool = vips_threadpool_new( im )) )
if( !(task = vips_task_new( im, &n_tasks )) )
return( -1 );
pool->start = start;
pool->allocate = allocate;
pool->work = work;
pool->a = a;
task->start = start;
task->allocate = allocate;
task->work = work;
task->a = a;
/* Attach workers and set them going.
/* Put the tasks to work.
*/
if( vips_threadpool_create_threads( pool ) ) {
vips_threadpool_free( pool );
return( -1 );
}
for( i = 0; i < n_tasks; i++ )
if( vips_threadpool_push( "worker", vips_task_run, task ) )
return( -1 );
for(;;) {
/* Wait for a tick from a worker.
*/
vips_semaphore_down( &pool->tick );
vips_semaphore_down( &task->tick );
VIPS_DEBUG_MSG( "vips_threadpool_run: tick\n" );
if( pool->stop ||
pool->error )
if( task->stop ||
task->error )
break;
if( progress &&
progress( pool->a ) )
pool->error = TRUE;
progress( task->a ) )
task->error = TRUE;
if( pool->stop ||
pool->error )
if( task->stop ||
task->error )
break;
}
/* Wait for them all to hit finish.
*/
vips_semaphore_downn( &pool->finish, pool->nthr );
vips_semaphore_downn( &task->finish, n_tasks );
/* Return 0 for success.
*/
result = pool->error ? -1 : 0;
result = task->error ? -1 : 0;
vips_threadpool_free( pool );
vips_task_free( task );
vips_image_minimise_all( im );
return( result );
}
/* Start up threadpools. This is called during vips_init.
/* Create a new threadpool. This is called during vips_init.
*/
void
vips__threadpool_init( void )
@ -999,6 +981,12 @@ vips__threadpool_init( void )
if( g_getenv( "VIPS_STALL" ) )
vips__stall = TRUE;
if( vips__concurrency == 0 )
vips__concurrency = vips__concurrency_get_default();
vips__pool = g_thread_pool_new( vips_thread_main_loop, NULL,
-1, FALSE, NULL );
}
/**
@ -1076,4 +1064,3 @@ vips_get_tile_size( VipsImage *im,
"groups of %d scanlines\n",
*tile_width, *tile_height, *n_lines );
}