In the parse_many function, we have one thread doing the stage 1, while the main thread does stage 2. So if stage 1 and stage 2 take half the time, the parse_many could run at twice the speed. It is unlikely to do so. Still, we see benefits of about 40% due to threading.
To achieve this interleaving, we load the data in batches (blocks) of some size. In the current code (master), we create a new thread for each batch. Thread creation is expensive so our approach only works over sizeable batches. This PR improves things and makes parse_many faster when using small batches.
This fixes our parse_stream benchmark which is just busted.
This replaces the one-thread per batch routine by a worker object that reuses the same thread. In benchmarks, this allows us to get the same maximal speed, but with smaller processing blocks. It does not help much with larger blocks because the cost of the thread create gets amortized efficiently.
This PR makes parse_many beneficial over small datasets. It also makes us less dependent on the thread creation time.
Unfortunately, it is going to be difficult to say anything definitive in general. The cost of creating a thread varies widely depending on the OS. On some systems, it might be cheap, in others very expensive. It should be expected that the new code will depend less drastically on the performances of the underlying system, since we create juste one thread.
Co-authored-by: John Keiser <john@johnkeiser.com>
Co-authored-by: Daniel Lemire <lemire@gmai.com>
* Fix for issue467
* Updating single-header
* Let us make it so that JsonStream is constructed from a padded_string which will avoid dangerous overruns.
* Fixing parse_stream
* Updating documentation.
* JsonStream threaded prototype
* JsonStream Threaded version working. Still supporting non-threaded version.
* Fix where invalid files would enter infinite loop.
* SingleHeader update
* I will remove -pthread in cmake for now.
* Attempt at resolving the -pthread issue
* rough prototype working. Needs more test and fine tuning.
* prototype working on large files.
* prototype working on large files.
* Adding benchmarks
* jsonstream API adjustment
* type
* minor fixes and cleaning.
* minor fixes and cleaning.
* removing warnings
* removing some copies
* runtime dispatch error fix
* makefile linking src/jsonstream.cpp
* fixing arm stage 1 headers
* fixing stage 2 headers
* fixing stage 1 arm header
* making jsonstream portable
* cleaning imports
* including <algorithms> for windows compiler
* cleaning benchmark imports
* adding jsonstream to amalgamation
* merged main into branch
* bug fix where JsonStream would bug on rare cases.
* Addind a JsonStream Demo to Amalgamation
* Fix for https://github.com/lemire/simdjson/issues/345
* Follow up test and fix for https://github.com/lemire/simdjson/issues/345 (#347)
* Final (?) fix for https://github.com/lemire/simdjson/issues/345
* Verbose basictest
* Being more forgiving of powers of ten.
* Let us zero the tail end.
* add basic fuzzers (#348)
* add basic fuzzing using libFuzzer
* let cmake respect cflags, otherwise the fuzzer flags go unnoticed
also, integrates badly with oss-fuzz
* add new fuzzer for minification, simplify the old one
* add fuzzer for the dump example
* clang format
* adding Paul Dreik
* rough prototype working. Needs more test and fine tuning.
* prototype working on large files.
* prototype working on large files.
* Adding benchmarks
* jsonstream API adjustment
* type
* minor fixes and cleaning.
* Fixing issue 351 (#352)
* Fixing issues 351 and 353
* minor fixes and cleaning.
* removing warnings
* removing some copies
* Fix ARM compile errors on g++ 7.4 (#354)
* Fix ARM compilation errors
* Update singleheader
* runtime dispatch error fix
* makefile linking src/jsonstream.cpp
* fixing arm stage 1 headers
* fixing stage 2 headers
* fixing stage 1 arm header
* fix integer overflow in subnormal_power10 (#355)
detected by oss-fuzz
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=18714
* Adding new test file, following https://github.com/lemire/simdjson/pull/355
* making jsonstream portable
* cleaning imports
* including <algorithms> for windows compiler
* cleaning benchmark imports
* adding jsonstream to amalgamation
* merged main into branch
* bug fix where JsonStream would bug on rare cases.
* Addind a JsonStream Demo to Amalgamation
* merging main
* rough prototype working. Needs more test and fine tuning.
* prototype working on large files.
* prototype working on large files.
* Adding benchmarks
* jsonstream API adjustment
* minor fixes and cleaning.
* minor fixes and cleaning.
* removing warnings
* removing some copies
* runtime dispatch error fix
* makefile linking src/jsonstream.cpp
* fixing arm stage 1 headers
* fixing stage 2 headers
* fixing stage 1 arm header
* making jsonstream portable
* cleaning imports
* including <algorithms> for windows compiler
* cleaning benchmark imports
* adding jsonstream to amalgamation
* bug fix where JsonStream would bug on rare cases.
* Addind a JsonStream Demo to Amalgamation
* rough prototype working. Needs more test and fine tuning.
* minor fixes and cleaning.
* adding jsonstream to amalgamation
* merged main into branch
* Addind a JsonStream Demo to Amalgamation
* merging main
* merging main
* make file fix
John Keiser
Daniel Lemire
Jeremie Piotte