Issue with one system v message queue for multiple process read/write
I am developing a server program that serves multiple clients by multiple child processes. I use only one System V message queue to communicate between parent process and child processes. Each process will wait for message with mtype equals to process ID. Each child process only communicate to parent process. In parent process, I call msgrcv with flag IPC_NOWAIT to prevent being blocked to process other stuffs. With 2 child processes, it works as expect, but when number of child processes increases, the issue will happen as follow:
- If I set flag on msgsnd to IPC_NOWAIT, some child processes cannot send message to parent process with error EAGAIN. If I add mechanism to re-send message with this kind of error, it still fails and parent process doesn't receive an message.
- If I unset flag on msgsnd from IPC_NOWAIT, some child processes will be blocked in this call to msgsnd function. The parent process doesn't receive any message.
So:
- How can I fix this issue?
- If not, can you recommend me an architect to solve my problem?
My system is Centos 7. The message has size of 300 bytes.
c++ c linux message-queue
asked Nov 13 '18 at 11:36
HungNVHungNV
11
add a comment |
I am developing a server program that serves multiple clients by multiple child processes. I use only one System V message queue to communicate between parent process and child processes. Each process will wait for message with mtype equals to process ID. Each child process only communicate to parent process. In parent process, I call msgrcv with flag IPC_NOWAIT to prevent being blocked to process other stuffs. With 2 child processes, it works as expect, but when number of child processes increases, the issue will happen as follow:
- If I set flag on msgsnd to IPC_NOWAIT, some child processes cannot send message to parent process with error EAGAIN. If I add mechanism to re-send message with this kind of error, it still fails and parent process doesn't receive an message.
- If I unset flag on msgsnd from IPC_NOWAIT, some child processes will be blocked in this call to msgsnd function. The parent process doesn't receive any message.
So:
- How can I fix this issue?
- If not, can you recommend me an architect to solve my problem?
My system is Centos 7. The message has size of 300 bytes.
c++ c linux message-queue
asked Nov 13 '18 at 11:36
HungNVHungNV
11
add a comment |
I am developing a server program that serves multiple clients by multiple child processes. I use only one System V message queue to communicate between parent process and child processes. Each process will wait for message with mtype equals to process ID. Each child process only communicate to parent process. In parent process, I call msgrcv with flag IPC_NOWAIT to prevent being blocked to process other stuffs. With 2 child processes, it works as expect, but when number of child processes increases, the issue will happen as follow:
- If I set flag on msgsnd to IPC_NOWAIT, some child processes cannot send message to parent process with error EAGAIN. If I add mechanism to re-send message with this kind of error, it still fails and parent process doesn't receive an message.
- If I unset flag on msgsnd from IPC_NOWAIT, some child processes will be blocked in this call to msgsnd function. The parent process doesn't receive any message.
So:
- How can I fix this issue?
- If not, can you recommend me an architect to solve my problem?
My system is Centos 7. The message has size of 300 bytes.
c++ c linux message-queue
asked Nov 13 '18 at 11:36
HungNVHungNV
11
I am developing a server program that serves multiple clients by multiple child processes. I use only one System V message queue to communicate between parent process and child processes. Each process will wait for message with mtype equals to process ID. Each child process only communicate to parent process. In parent process, I call msgrcv with flag IPC_NOWAIT to prevent being blocked to process other stuffs. With 2 child processes, it works as expect, but when number of child processes increases, the issue will happen as follow:
- If I set flag on msgsnd to IPC_NOWAIT, some child processes cannot send message to parent process with error EAGAIN. If I add mechanism to re-send message with this kind of error, it still fails and parent process doesn't receive an message.
- If I unset flag on msgsnd from IPC_NOWAIT, some child processes will be blocked in this call to msgsnd function. The parent process doesn't receive any message.
So:
- How can I fix this issue?
- If not, can you recommend me an architect to solve my problem?
My system is Centos 7. The message has size of 300 bytes.
c++ c linux message-queue
c++ c linux message-queue
asked Nov 13 '18 at 11:36
HungNVHungNV
11
asked Nov 13 '18 at 11:36
HungNVHungNV
11
asked Nov 13 '18 at 11:36
HungNVHungNV
11
asked Nov 13 '18 at 11:36
HungNVHungNV
11
asked Nov 13 '18 at 11:36
HungNVHungNV
11
11
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Code is not given. Best is to check return values of failure and refer manpage . On gdb you can single step through to get to point where child process fails to send message
answered Nov 13 '18 at 12:15
anandanand
1275
I cannot use gdb because it happens random when have multiple process, so I don't know which child process will be blocked to switch gdb to. The code is part of my company so I cannot share.
– HungNV
Nov 13 '18 at 13:19
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53280183%2fissue-with-one-system-v-message-queue-for-multiple-process-read-write%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Code is not given. Best is to check return values of failure and refer manpage . On gdb you can single step through to get to point where child process fails to send message
answered Nov 13 '18 at 12:15
anandanand
1275
I cannot use gdb because it happens random when have multiple process, so I don't know which child process will be blocked to switch gdb to. The code is part of my company so I cannot share.
– HungNV
Nov 13 '18 at 13:19
add a comment |
Code is not given. Best is to check return values of failure and refer manpage . On gdb you can single step through to get to point where child process fails to send message
answered Nov 13 '18 at 12:15
anandanand
1275
I cannot use gdb because it happens random when have multiple process, so I don't know which child process will be blocked to switch gdb to. The code is part of my company so I cannot share.
– HungNV
Nov 13 '18 at 13:19
add a comment |
Code is not given. Best is to check return values of failure and refer manpage . On gdb you can single step through to get to point where child process fails to send message
answered Nov 13 '18 at 12:15
anandanand
1275
Code is not given. Best is to check return values of failure and refer manpage . On gdb you can single step through to get to point where child process fails to send message
answered Nov 13 '18 at 12:15
anandanand
1275
answered Nov 13 '18 at 12:15
anandanand
1275
answered Nov 13 '18 at 12:15
anandanand
1275
answered Nov 13 '18 at 12:15
anandanand
1275
1275
I cannot use gdb because it happens random when have multiple process, so I don't know which child process will be blocked to switch gdb to. The code is part of my company so I cannot share.
– HungNV
Nov 13 '18 at 13:19
add a comment |
I cannot use gdb because it happens random when have multiple process, so I don't know which child process will be blocked to switch gdb to. The code is part of my company so I cannot share.
– HungNV
Nov 13 '18 at 13:19
I cannot use gdb because it happens random when have multiple process, so I don't know which child process will be blocked to switch gdb to. The code is part of my company so I cannot share.
– HungNV
Nov 13 '18 at 13:19
I cannot use gdb because it happens random when have multiple process, so I don't know which child process will be blocked to switch gdb to. The code is part of my company so I cannot share.
– HungNV
Nov 13 '18 at 13:19
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53280183%2fissue-with-one-system-v-message-queue-for-multiple-process-read-write%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
