ac7045b75f
This adds a semaphore to throttle the number of FileSystem instances which can be created simultaneously, set in "fs.creation.parallel.count". This is designed to reduce the impact of many threads in an application calling FileSystem.get() on a filesystem which takes time to instantiate -for example to an object where HTTPS connections are set up during initialization. Many threads trying to do this may create spurious delays by conflicting for access to synchronized blocks, when simply limiting the parallelism diminishes the conflict, so speeds up all threads trying to access the store. The default value, 64, is larger than is likely to deliver any speedup -but it does mean that there should be no adverse effects from the change. If a service appears to be blocking on all threads initializing connections to abfs, s3a or store, try a smaller (possibly significantly smaller) value. Contributed by Steve Loughran. |
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