This is better for performance because these then don't need to be reevaluated every time they are called.
When encountering an unqualified function or constant reference, PHP will first try to locate a symbol in the current namespace by that name, and then fall back to the global namespace.
This short-circuits the check, which has substantial performance effects in some cases - in particular, ord(), chr() and strlen() show ~1500x faster calls when they are fully qualified.
However, this doesn't mean that PM is getting a massive amount faster. In real world terms, this translates to about 10-15% performance improvement.
But before anyone gets excited, you should know that the CodeOptimizer in the PreProcessor repo has been applying fully-qualified symbol optimizations to Jenkins builds for years, which is one of the reasons why Jenkins builds have better performance than home-built or source installations.
We're choosing to do this for the sake of future SafePHP integration and also to be able to get rid of the buggy CodeOptimizer, so that phar and source are more consistent.
Since 3.2 there have been some runtime performance issues related to garbage collection and dynamic AsyncWorker booting. This is partly because of GC being dumb about shutting down what it thinks are "unused" workers. A worker which has been idle for a single tick is considered the same as a worker which has been idle for hours. The result of this is that on active servers, workers would get shut down and then immediately restarted because of something like chunk sending. Since booting an async worker is frightfully expensive, this causes lag spikes, which is obviously bad.
This commit changes the GC mechanism to only shutdown workers which have not been used for the last 5 minutes.
This greatly improves GC performance by being more intelligent about how it collects garbage tasks. It knows that if X task in the queue is not finished, none of the tasks behind it can be finished either, so there's no point checking them.
This also presents the opportunity to cleanup a lot of async pool internals, so I've taken it and torched a lot of garbage.
This is now self-maintaining and doesn't rely on the async pool to wipe its ass on task completion. Instead, the garbage collector will cause thread-local data to be automatically released when the async task is garbage-collected on the main thread.
This brings two plugin-breaking changes: AsyncTask->onCompletion() and AsyncTask->onProgressUpdate() no longer accept Server parameters.
This now allows for the functionality of AsyncPool and AsyncTask to be tested outside of a Server.
This changes how the AsyncPool works so that it does not immediately always start all of the workers in the pool.
Instead, workers will be started only when an idle worker was not found.
This allows for significant memory footprint reductions while idle.
In effect the async-workers setting in pocketmine.yml now dictates a _maximum_ pool size, not a fixed pool size.
This commit contains quite a few breaking changes with respect to how AsyncTasks are handled. This is necessary to allow separation of the ServerScheduler and the AsyncPool, because in the future the ServerScheduler may be removed and instead there will be isolated per-plugin sync-task schedulers - but we cannot have every plugin with its own worker pool for memory usage reasons if nothing else.
The following things have changed:
- ServerScheduler: scheduleAsyncTask(), scheduleAsyncTaskToWorker(), getAsyncTaskPoolSize(), increaseAsyncTaskPoolSize() and similar methods have all been removed. Additionally the static \$WORKERS field has been removed.
- Server: added API method getAsyncPool(). This grants you direct access to the server's AsyncPool. Calls to getScheduler()->scheduleAsyncTask() and scheduleAsyncTaskToWorker() should be replaced with getAsyncPool()->submitTask() and submitTaskToWorker() respectively.
this implementation was god-awful bad and it was entirely avoidable to make it this complicated.
This utilizes the fact that pthreads treats static properties as thread-local. AsyncTask local storage now utilizes a \SplObjectStorage stored in an AsyncTask private static field.
