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Experimented with multithreading the indexing pipeline. Left undef'd as 15%-30% improvement of indexing time does not seem worth the complexity

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This commit is contained in:
Jean-Francois Dockes
2012-02-21 17:09:02 +01:00
parent 26914a823c
commit 9bc2fc8958
8 changed files with 487 additions and 9 deletions
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src/utils/workqueue.cpp
+102
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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include "workqueue.h"
static char *thisprog;
static char usage [] =
" \n\n"
;
static void
Usage(void)
{
fprintf(stderr, "%s: usage:\n%s", thisprog, usage);
exit(1);
}
static int op_flags;
#define OPT_MOINS 0x1
#define OPT_s 0x2
#define OPT_b 0x4
class Task {
public:
Task()
: m_id(o_id++)
{}
int m_id;
static int o_id;
};
int Task::o_id;
void *worker(void *vtp)
{
fprintf(stderr, "Worker working\n");
WorkQueue<Task> *tqp = (WorkQueue<Task> *)vtp;
Task tsk;
for (;;) {
if (!tqp->take(&tsk)) {
fprintf(stderr, "Worker: take failed\n");
return (void*)0;
}
fprintf(stderr, "WORKER: got task %d\n", tsk.m_id);
if (tsk.m_id > 20) {
tqp->workerExit();
break;
}
}
return (void*)1;
}
int main(int argc, char **argv)
{
int count = 10;
thisprog = argv[0];
argc--; argv++;
while (argc > 0 && **argv == '-') {
(*argv)++;
if (!(**argv))
/* Cas du "adb - core" */
Usage();
while (**argv)
switch (*(*argv)++) {
case 's': op_flags |= OPT_s; break;
case 'b': op_flags |= OPT_b; if (argc < 2) Usage();
if ((sscanf(*(++argv), "%d", &count)) != 1)
Usage();
argc--;
goto b1;
default: Usage(); break;
}
b1: argc--; argv++;
}
if (argc != 0)
Usage();
WorkQueue<Task> wq(10);
if (!wq.start(&worker, &wq)) {
fprintf(stderr, "Start failed\n");
exit(1);
}
for (;;) {
Task tsk;
fprintf(stderr, "BOSS: put task %d\n", tsk.m_id);
if (!wq.put(tsk)) {
fprintf(stderr, "Boss: put failed\n");
exit(1);
}
if ((tsk.m_id % 10) == 0)
sleep(1);
}
exit(0);
}
src/utils/workqueue.h
+195
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@@ -0,0 +1,195 @@
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the
* Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifndef _WORKQUEUE_H_INCLUDED_
#define _WORKQUEUE_H_INCLUDED_
#include "pthread.h"
#include <string>
#include <queue>
using std::queue;
using std::string;
/**
* A WorkQueue manages the synchronisation around a queue of work items,
* where a single client thread queues tasks and a single worker takes
* and executes them. The goal is to introduce some level of
* parallelism between the successive steps of a previously single
* threaded pipe-line (data extraction / data preparation / index
* update).
*
* There is no individual task status return. In case of fatal error,
* the client or worker sets an end condition on the queue. A second
* queue could conceivably be used for returning individual task
* status.
*/
template <class T> class WorkQueue {
public:
WorkQueue(int hi = 0, int lo = 1)
: m_high(hi), m_low(lo), m_size(0), m_worker_up(false),
m_worker_waiting(false), m_jobcnt(0), m_lenacc(0)
{
m_ok = (pthread_cond_init(&m_cond, 0) == 0) &&
(pthread_mutex_init(&m_mutex, 0) == 0);
}
~WorkQueue()
{
if (m_worker_up)
setTerminateAndWait();
}
/** Start the worker thread. The start_routine will loop
* taking and executing tasks. */
bool start(void *(*start_routine)(void *), void *arg)
{
bool status = pthread_create(&m_worker_thread, 0,
start_routine, arg) == 0;
if (status)
m_worker_up = true;
return status;
}
/**
* Add item to work queue. Sleep if there are already too many.
* Called from client.
*/
bool put(T t)
{
if (!ok() || pthread_mutex_lock(&m_mutex) != 0)
return false;
while (ok() && m_high > 0 && m_queue.size() >= m_high) {
// Keep the order: we test ok() AFTER the sleep...
if (pthread_cond_wait(&m_cond, &m_mutex) || !ok()) {
pthread_mutex_unlock(&m_mutex);
return false;
}
}
m_queue.push(t);
++m_size;
pthread_cond_broadcast(&m_cond);
pthread_mutex_unlock(&m_mutex);
return true;
}
/** Wait until the queue is empty and the worker is
* back waiting for task. Called from the client when it needs to
* perform work that couldn't be done in parallel with the
* worker's tasks.
*/
bool waitIdle()
{
if (!ok() || pthread_mutex_lock(&m_mutex) != 0)
return false;
// We're done when the queue is empty AND the worker is back
// for a task (has finished the last)
while (ok() && (m_queue.size() > 0 || !m_worker_waiting)) {
if (pthread_cond_wait(&m_cond, &m_mutex)) {
pthread_mutex_unlock(&m_mutex);
return false;
}
}
pthread_mutex_unlock(&m_mutex);
return ok();
}
/** Tell the worker to exit, and wait for it. There may still
be tasks on the queue. */
void* setTerminateAndWait()
{
if (!m_worker_up)
return (void *)0;
pthread_mutex_lock(&m_mutex);
m_ok = false;
pthread_cond_broadcast(&m_cond);
pthread_mutex_unlock(&m_mutex);
void *status;
pthread_join(m_worker_thread, &status);
m_worker_up = false;
return status;
}
/** Remove task from queue. Sleep if there are not enough. Signal if we go
to sleep on empty queue: client may be waiting for our going idle */
bool take(T* tp)
{
if (!ok() || pthread_mutex_lock(&m_mutex) != 0)
return false;
while (ok() && m_queue.size() < m_low) {
m_worker_waiting = true;
if (m_queue.empty())
pthread_cond_broadcast(&m_cond);
if (pthread_cond_wait(&m_cond, &m_mutex) || !ok()) {
pthread_mutex_unlock(&m_mutex);
m_worker_waiting = false;
return false;
}
m_worker_waiting = false;
}
++m_jobcnt;
m_lenacc += m_size;
*tp = m_queue.front();
m_queue.pop();
--m_size;
pthread_cond_broadcast(&m_cond);
pthread_mutex_unlock(&m_mutex);
return true;
}
/** Take note of the worker exit. This would normally happen after an
unrecoverable error */
void workerExit()
{
if (!ok() || pthread_mutex_lock(&m_mutex) != 0)
return;
m_ok = false;
pthread_cond_broadcast(&m_cond);
pthread_mutex_unlock(&m_mutex);
}
/** Debug only: as the size is returned while the queue is unlocked, there
* is no warranty on its consistency. Not that we use the member size, not
* the container size() call which would need locking.
*/
size_t size() {return m_size;}
private:
bool ok() {return m_ok && m_worker_up;}
size_t m_high;
size_t m_low;
size_t m_size;
bool m_worker_up;
bool m_worker_waiting;
int m_jobcnt;
int m_lenacc;
pthread_t m_worker_thread;
queue<T> m_queue;
pthread_cond_t m_cond;
pthread_mutex_t m_mutex;
bool m_ok;
};
#endif /* _WORKQUEUE_H_INCLUDED_ */