danog/parallel
1
0
Fork 0
mirror of https://github.com/danog/parallel.git synced 2024-11-26 20:34:40 +01:00
Code Issues Projects Releases Wiki Activity

Update documentation

Browse Source
This commit is contained in:
Aaron Piotrowski 2015-09-27 23:45:56 -05:00
parent 8695d600fc
commit cf1455b239
1 changed files with 68 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

100
README.md
View File

@ -1,5 +1,4 @@
# Concurrency for Icicle
**Under development -- keep an eye out for things to come in the near future though!**
**True concurrency using native threading and multiprocessing for parallelizing code, *without* blocking.**
@ -13,36 +12,65 @@ This library is a component for [Icicle](https://github.com/icicleio/icicle) tha
This library provides a means of parallelizing code without littering your application with complicated lock checking and inter-process communication.
To be as flexible as possible, this library comes with a collection of non-blocking concurrency tools that can be used independently as needed, as well as an "opinionated" task API that allows you to assign units of work to a pool of worker threads or processes.
To be as flexible as possible, this library comes with a collection of non-blocking concurrency tools that can be used independently as needed, as well as an "opinionated" worker API that allows you to assign units of work to a pool of worker threads or processes.
##### Requirements
#### Requirements
- PHP 5.5+
- [pthreads](http://pthreads.org) for multithreading *or*
- System V-compatible Unix OS and PHP with `--enable-pcntl`
#### Benchmarks
##### Suggested
- [pthreads extension](https://pecl.php.net/package/pthreads): Best extension option for concurrency in PHP, but it requires PHP to be compiled with `--enable-maintainer-zts` to enable thread-safety.
*or*
- [pcntl extension](http://php.net/manual/en/book.pcntl.php): Enables forking concurrency method.
- [sysvmsg extension](http://php.net/manual/en/book.sem.php): Required for sharing memory between forks or processes.
##### Installation
The recommended way to install is with the [Composer](http://getcomposer.org/) package manager. (See the [Composer installation guide](https://getcomposer.org/doc/00-intro.md) for information on installing and using Composer.)
Run the following command to use Icicle in your project:
```bash
composer require icicleio/concurrent
```
You can also manually edit `composer.json` to add this library as a project requirement.
```js
// composer.json
{
"require": {
"icicleio/concurrent": "^0.1"
}
}
```
While the pthreads is not necessary for this package, it is the fastest and best choice for concurrency in PHP. To enable threading, you will need to compile pthreads from source, as this package depends on unstable and unreleased fixes in pthreads.
```bash
git clone https://github.com/krakjoe/pthreads && cd pthreads
git checkout master
phpize
./configure
make
sudo make install
```
##### Benchmarks
A few benchmarks are provided for analysis and study. Can be used to back up implementation decisions, or to measure performance on different platforms or hardware.
vendor/bin/athletic -p benchmarks -b vendor/autoload.php
## Installation
With [Composer](http://getcomposer.org). What did you expect?
composer require icicleio/concurrent
To enable threading, you will need to compile pthreads from source, as this package depends on unstable and unreleased fixes in pthreads.
git clone https://github.com/krakjoe/pthreads && cd pthreads
git checkout master
phpize
./configure
make
sudo make install
```bash
vendor/bin/athletic -p benchmarks -b vendor/autoload.php
```
## Documentation
Concurrent can use either process forking or true threading to parallelize execution. Threading provides better performance and is compatible with Unix and Windows but requires ZTS (Zend thread-safe) PHP, while forking has no external dependencies but is only compatible with Unix systems. If your environment works meets neither of these requirements, this library won't work.
Concurrent can use either process forking, processes created using `proc_open()`, or true threading to parallelize execution. Threading provides better performance and is compatible with Unix and Windows but requires ZTS (Zend thread-safe) PHP, while forking has no external dependencies but is only compatible with Unix systems.
### Threads
Threading is a cross-platform concurrency method that is fast and memory efficient. Thread contexts take advantage of an operating system's multi-threading capabilities to run code in parallel. A spawned thread will run completely parallel to the parent thread, each with its own environment. Each thread is assigned a closure to execute when it is created, and the returned value is passed back to the parent thread. Concurrent goes for a "shared-nothing" architecture, so any variables inside the closure are local to that thread and can store any non-safe data.
You can spawn a new thread with the `Thread::spawn()` method:
@ -66,6 +94,7 @@ Loop\run();
You can wait for a thread to finish by calling `join()`. Joining does not block the parent thread and will asynchronously wait for the child thread to finish before resolving.
### Forks
For Unix-like systems, you can create parallel execution using fork contexts. Though not as efficient as multi-threading, in some cases forking can take better advantage of some multi-core processors than threads. Fork contexts use the `pcntl_fork()` function to create a copy of the current process and run alternate code inside the new process.
Spawning and controlling forks are quite similar to creating threads. To spawn a new fork, use the `Fork::spawn()` method:
@ -88,7 +117,8 @@ Loop\run();
Calling `join()` on a fork will asynchronously wait for the forked process to terminate, similar to the `pcntl_wait()` function.
#### Synchronization with channels
#### Synchronization with Channels
Threads and forks wouldn't be very useful if they couldn't be given any data to work on. The recommended way to share data between contexts is with a `Channel`. A channel is a low-level abstraction over local, non-blocking sockets, which can be used to pass messages and objects between two contexts. Channels are non-blocking and do not require locking. For example:
```php
@ -98,25 +128,31 @@ use Icicle\Coroutine;
use Icicle\Loop;
Coroutine\create(function () {
list($socketA, $socketB) = Channel::createSocketPair();
$channel = new Channel($socketA);
$thread = Thread::spawn(function () {
$time = (yield $this->receive()); // Receive from the parent.
sleep($time);
yield $this->send("Hello!"); // Send to the parent.
});
$thread = Thread::spawn(function ($socketB) {
$channel = new Channel($socketB);
yield $channel->send("Hello!");
}, $socketB);
yield $thread->send(3); // Send 3 to the context.
$message = (yield $channel->receive());
$message = (yield $thread->receive()); // Receive from the context.
yield $thread->join();
print $message . "\n";
});
Loop\run();
```
### Synchronization with parcels
Thread and fork execution contexts include a channel to communicate with the parent and context. The channel methods `send()` and `receive()` may be invoked using `$this` within the function executed in the context and on the context object in the parent. See the example above.
#### Synchronization with Parcels
Parcels are shared containers that allow you to store context-safe data inside a shared location so that it can be accessed by multiple contexts. To prevent race conditions, you still need to access a parcel's data exclusively, but Concurrent allows you to acquire a lock on a parcel asynchronously without blocking the context execution, unlike traditional mutexes.
## Development and contributing
### Development and Contributing
Interested in contributing to Icicle? Please see our [contributing guidelines](https://github.com/icicleio/icicle/blob/master/CONTRIBUTING.md) in the [Icicle repository](https://github.com/icicleio/icicle).
Want to hack on the source? A [Vagrant](http://vagrantup.com) box is provided with the repository to give a common development environment for running concurrent threads and processes, and comes with a bunch of handy tools and scripts for testing and experimentation.