Greetings, just a few thoughts regarding multi-threading support. In my job, I'm maintaining the VM source code of the Digitalk Smalltalk VM. I have made some considerations how Smalltalk could support native multi-threading and there are a lot of hurdles to overcome:
- the garbage collector: also a multi-threaded garbage collector is required, which is quite complex. Each thread needs at least it's own "short term object heap". Even in Java a full GC requires a "world stop" and each thread must have reached a so called "safe point" to make a full GC work. This requires special means of synchronization for each thread. - the language needs new keywords to deal with synchronization issues. - many base classes must be rewritten to be thread safe - probably a lot of other problems may exist, that are not visible in the first place To my knowledge currently no Smalltalk implementation exists, which can do multi-threading. The basic design was done in the 70ties and early 80ties and multi-threading has not been considered during that era. Afaik only Java and C# have a VM that supports automatic garbage collection with multiple native threads. I don't know about C#, but the team working on JDK is about 580 people (at least this is number of different committers on the github project). Imho a considerable effort is needed, which would only be done, if there is a "strong need" and a team of clever people who might achieve this. Smalltalk is only a niche system and the user base is declining more and more, so I hardly see any reason, why anybody would invest in such a project. Best regards, Andreas On 05.02.2022 21:09, Blake McBride wrote:
Greetings, One of the things that have kept me from all Smalltalks is the lack of true/native multi-threading support that is able to utilize multiple CPUs. In today's world, it is a show-stopper for me and many others. I believe that GST only supports cooperative threads utilizing a single machine thread. Adding true native thread support would make GST quite appealing to a large crowd IMO. I'd also guess that adding said support would be difficult but easier in GST than other Smalltalks. Just a thought. Thanks! Blake McBride
