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digitalmars.D.learn - Spurious error: Process does not exist or is not a child process.

reply Andre Pany <andre s-e-a-p.de> writes:
Hi,

I compiled a linux application on my pc (Windows subsystem for 
Linux) and copied it to AWS EMR (linux) system.

The application should execute the console application "aws". 
Most of the time
the exception "Process does not exist or is not a child process." 
is raised.
If I execute the application a second later, the error is not 
thrown.

The command hardcoded:
auto aws =  executeShell(`aws sqs get-queue-url --cli-input-json 
"file:///tmp/awsd2159b505cfc4c0ab1a80a53b7d9999d.json" 
--no-paginate --output json --cli-read-timeout 10 
--cli-connect-timeout 10 --region eu-central-1`);

??:?  trusted int std.process.Pid.performWait(bool) [0x737247]
??:?  safe int std.process.wait(std.process.Pid) [0x780b71]
??:? std.typecons.Tuple!(int, "status", immutable(char)[], 
"output").Tuple 
std.process.executeImpl!(std.process.pipeShell(const(char[]), 
std.process.Redirect, 
const(immutable(char)[][immutable(char)[]]), std.process.Config, 
const(char[]), immutable(char)[]), const(char)[], 
immutable(char)[]).executeImpl(const(char)[], 
const(immutable(char)[][immutable(char)[]]), std.process.Config, 
ulong, const(char[]), immutable(char)[]) [0x737de5]
??:?  trusted std.typecons.Tuple!(int, "status", 
immutable(char)[], "output").Tuple 
std.process.executeShell(const(char[]), 
const(immutable(char)[][immutable(char)[]]), std.process.Config, 
ulong, const(char[]), immutable(char)[]) [0x737356]
dependencies/aws-sdk-0.0.5/core/aws/sdk/core/client.d:126 
immutable(char)[] 
aws.sdk.core.client.AwsClient.executeRaw(immutable(char)[]) 
[0x63ee58]

Can you think of any reason why the executeShell function 
sometimes works and sometimes not?

Kind regards
André
Apr 11 2018
parent Andre Pany <andre s-e-a-p.de> writes:
On Thursday, 12 April 2018 at 06:45:36 UTC, Andre Pany wrote:

 Hi,

 I compiled a linux application on my pc (Windows subsystem for 
 Linux) and copied it to AWS EMR (linux) system.


I found the issue. In addition to the AWS client I also start 
other applications which might
become zombie processes. For these processes I added this coding:

signal(SIGCHLD, &handleSigChld);

extern (C) void handleSigChld(int sig) nothrow  nogc  system
     {

         import core.sys.posix.sys.wait : waitpid, WNOHANG;

         int status;
         waitpid(-1, &status, WNOHANG);
     }

But this coding has a bad influence on the AWS client causing 
spurious exceptions.

Kind regards
André
Apr 12 2018