Changing maximum number of open files for your running process
lazarus / 32-Linux

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Molochnik · 2024-01-01 22:55

Is it possible to change the maximum number of open files for your
currently running process?
I tried different approaches but failed
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i    if
RunCommand('/bin/bash',['-c','ps -C testapp -o pid='],s) then   
 writeln(s);// finding your currently running pid  if
RunCommand('/bin/bash',['-c','prlimit --pid ' + s.trim + '
--nofile=1024:1024'],s) then     writeln(s);// changing max number of
the open files to 1024 via prlimit, RunCommand fails  if
RunCommand('/bin/bash',['-c','ulimit -Sn 1024'],s) then   
 writeln(s);// changing max number of the open files to 1024 via
ulimit, no error and no result   if
RunCommand('/bin/bash',['-c','ulimit -Sn'],s) then     writeln(s);//
shows the maximum number of open files, works fine, the return value
is always the same

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Kays · 2024-01-04 02:18

Quote from: Molochnik on January 01, 2024, 11:55:32 pmIs it possible
to change the maximum number of open files for your currently running
process?Yes.Quote from: Molochnik on January 01, 2024, 11:55:32 pmI
tried different approaches but failedThe resource limits apply to the
current process. RunCommand spawns a new process so any changes do not
propagate to the parent process. You will need to utilize the
setrlimit system call directly.Code: Pascal
 [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
fileHoarder(input, output, stdErr);{$typedAddress on}uses       
errors, math, baseUnix;const        minimumMaximumNumberOfFiles =
19479;var        limit: tRLimit;begin           { What limits does the
current process have? }        case fpGetRLimit(rLimit_noFile, @limit)
of                { failure }                -1:                begin 
                      pError('Could not obtain maximum open files
resource limits',                                fpGetErrno);        
              halt;                end;                { success }   
            0: ;        end;                { Current soft limit below
the minimum maximum? }        if limit.rLim_cur <
minimumMaximumNumberOfFiles then        begin                { Raise
soft limit. The hard limit requires extra privileges. }              
limit.rLim_cur := minimumMaximumNumberOfFiles;                { Soft
limit argument may not exceed the hard limit argument. }             
 limit.rLim_max := max(limit.rLim_max, limit.rLim_cur);              
                case fpSetRLimit(rLimit_noFile, @limit) of           
           { failure }                        -1:                    
  begin                                writeLn(stdErr, 'Error: Could
not raise maximum open files resource limit.');                      
        case fpGetErrno of                                       
eSYsEInval:                                        begin             
                                 writeLn(stdErr, 'A programming
mistake caused the invalid parameter',                               
                       'tRLimit[rLim_cur: ', limit.rLim_cur:1,       
                                               '; rLim_max: ',
limit.rLim_max:1, '].');                                        end; 
                                     eSysEPerm:                      
                begin                                               
writeLn(stdErr, 'The raised limits exceed the system’s hard
limits.');                                        end;               
               end;                                halt;             
         end;                        { success }                     
  0: ;                end;        end;                { Optional:
Let’s verify our result. }        case fpGetRLimit(rLimit_noFile,
@limit) of                { success }                 0:             
 begin                        writeLn('I can have up to ',
limit.rLim_cur:1, ' open files.');                end;        end;end.

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Molochnik · 2024-01-04 16:30

Kays
That works perfect! Thank you very much!