[SOLVED] How to set proper values for TThread Policy and Priority in Delphi 10.3 and Linux64 Compiler

How to set proper values for TThread Policy and Priority in Delphi 10.3 and Linux64 Compiler

Within my Delphi Linux application I like to set a thread priority to "tpTimeCritical". Unfortunately the priority value cannot be changed. Every value <> 0 throws a Runtime Error 217.

I found out that on Linux the policy has to be changed first (SCHED_FIFO or SCHED_RR). In sched.h I have the following values:

#define SCHED_NORMAL    0
#define SCHED_FIFO      1
#define SCHED_RR        2
#define SCHED_BATCH     3
#define SCHED_IDLE      5
#define SCHED_DEADLINE  6

After the policy has been set correctly, the priority should be set to a value between 1 and 99. Unfortunately this does not work.

constructor TMyThread.Create;
begin
   inherited Create(True);

   Policy   := 1;
   Priority := 90;
end;

Solution

After my inquiry about this with Embarcadero (RSP-26280) it turned out to be a bug in the corresponding Linux thread implementation. The bug was fixed in June 2020 and the fix was included in the next official release (I think 10.4).