Re-enable the D Garbage Collector

[markisaa]

We disabled the garbage collector for easy debugging and development. This must be re-enabled before we can ship this to clients. This will likely be a very involved change.

@andralex - Assigning to you, as I believe you mentioned you would be willing to make a pass at this in one of our meetings.

[Gary-Li]

Hi, has this issue been fixed? My problem is when I try to preview different table data in Tableau, the memory keep increased. So I tried to remove GC.disable() code from driver.d, but the Driver keep crashed when create Presto connection in Tableau. Did I missed anything? And what's the right way to enable GC in presto-odbc?
Thanks in advance!

[markisaa]

No this has not been worked on. For now, you will just need to work with it even though it leaks memory.

With the change you suggested you did successfully re-enable the garbage collector, but the code is not written to make proper use of the GC. The GC will not realize that there are references out in C code that point to memory in D... it will then deallocate such pieces of memory (thinking nobody has a reference to them), resulting in a segfault. There are quite a few not-so-obvious holes to patch up before the GC can be re-enabled safely; this is no small job. In the end the goal is to allocate almost nothing via the GC.

[Gary-Li]

I see. Thanks @markisaa !