Memory leak in rare cases using foreach and parallel

[Guillaume Lathoud]

Hello,

In a number-crunching app that tries many different configuration 
parameters, I observed in some rare cases a memory leak when 
doing:


     class Cfg { /* ...configuration parameters...*/ }

     auto cfg_range; // range that spits out the many 
configurations (instances of Cfg)

     foreach (cfg; parallel( cfg_range ))
     {
        // Do one computation for the set of parameters `cfg`
     }

using LDC 1.10.0 (based on dmd 2.080.1) on a linux machine.

This was difficult to reduce to a simple use case. The memory 
leak happened in rare cases, but in those cases, it always 
happened.

The workaround I found looked like this:

     foreach (i; parallel( cfg_range.length.iota ))
     {
       auto cfg = cfg_range[ i ];
       // Do one computation for the set of parameters `cfg`
     }

Hopefully this helps anyone encountering a similar issue and/or 
LDC developers.

Best regards,
Guillaume