Watching / Capturing An Applications Threads

Hi ,
In my program, for a process A executing operation, there are multiple threads created.
One of the thread A checks whether process is active or not
Second thread B executes a function
One of the periodic thread C calls a callback function that executes an audit after every 30 secs.

In the audit , the function uses g_spawn_commmand_line_sync() function to spawn a child process that executes a command line (shell script).

Since g_spawn_commmand_line_sync() spawns a new child process .
In the error case scenario, the spawned child process got stuck and became zombie process. It did not get killed.Also it acquired sockets which were assigned to a thread B executing operation.

Even though the thread B got terminated ,the child process did not release the sockets that were connected to it.


My question is ,I have to automate this in C program that if it finds spawned process of g_spawn_commmand_line_sync() defunct, the
health check thread B should be able to clean it without klling the main process.

i could not find any spawn function that will help me find the PID of g_spawn_commmand_line_sync() spawned process.

I get the details from ps commands. But how can I find it in a c-program?

Hi all,

In my work, I'd like to spawn separate kernel threads (tasks) to execute syscall asynchronously. Specifically, a user thread issues a syscall, goes into kernel, save the syscall number and arguments somewhere in the kernel address space, but does not execute the syscall. A kernel thread which is different from the user thread, will fetch the syscall number and arguments to execute the syscall on behalf of the user thread.
But for file operations such as read, the kernel thread is not aware of the open files of the user threads. For example, if the user thread opens a file and get a file descriptor, then it issue a read() syscall. The kernel thread cannot execute the read() on behalf of the user thread by just using the file descriptor. Thus I need some way to allow the kernel thread share the open files information with the user thread, such that the kernel thread will have the context of the open file to execute read(). I tried to pass the files_struct of the user thread's task_struct to the kernel thread, but it didn't help, read() returns a EFAULT error.
Can anyone give me some suggestions on how to make a kernel thread share the open files with a user thread? Or more straightforward how to execute the read() syscall in the example above in kernel thread? Thank you very much!

--Louis

I have written a script to start a virtual machine through pass through mode and port number.

I start the guest linux through Run command from windows
telnet <baseIP> <portNUm>

Then after connecting to that guest machine,

each enter taking twice.

Any help will be greatful

If you run this command on your computer, how many active and passive connections openings are you typically supposed to have? Specifically, for a firewalled home PC behind a wifi router/cable modem combination. Can someone explain the purpose of this command?

Hi,

I have been trying to get information on how to process the output of a tcl file (aodv and leach protocol using mannasim) which I got on my command line Iinterface. Actually, I don't even know the keywords to search as I am new to this and other minor attempts haven't yielded positive results., I know there is usually a trace file but I can't see any. All I see is on my command line.

I also observe that it took the space on the entire screen and I can't copy the output from the start ( I could only copy from node 19 out of 30 nodes) because of the huge number of output lines.

The last thing I havent been able to figure ou is whether temperature is equivalent to energy Iin mannasim as mannasim has only temperature and carbon dioxide?


Thanks

can anyone explain me the exact difference between process task and threads??
thanks in advance!!!

Hi all,
I am brand new to Linux, playing around a bit with different things to see how I can use it in the future. Here is my problem:

I have written a simple program in Ada that works well on windows. It opens a TCP port (20000) and listens for incoming connections. I tried it on my internal network and it works well. I can connect from other windows machines and even from my Linux machine.

Now I moved the program to Linux and compiled it there. It starts ok and then listens for the connections. I can connect to it from that same Linux machine but not from any other machine on my network.

I checked the firewall status on Linux with ufw status and it is disabled. I also tried to add a rule to the iptables with
iptables -A INPUT -p tcp --dport 20000 -j ACCEPT

but still nothing. I can not connect from another machine on my network. I also tried to open a simple telnet connection from a windows machine and that too is blocked. I thought without the firewall all incoming connections would be allowed but obviously something is not working as I thought.

Any help would be greatly appreciated

Hello,

I am troubleshooting something and I got this problem.

If I do "pstree -p"

It shows,

Code:

        ├─soffice.bin(7734)─┬─{soffice.bin}(7735)
        │                   ├─{soffice.bin}(7736)
        │                   ├─{soffice.bin}(7737)
        │                   └─{soffice.bin}(7743)

However, it does NOT show up in "ps -elf"

Code:

ps -elf | grep soffi
0 S whho      7734     1  0  80   0 - 36435 -      11:14 pts/2    00:00:03 /usr/lib/openoffice/program/soffice.bin -splash-pipe=5
0 S whho      7833  7759  0  80   0 -   751 -      11:21 pts/3    00:00:00 grep soffi

I was wondering if 7735, 7736, 7737, 7743 were really processes. Then I checked /proc, I could cd to /proc/7735, /proc/7736, etc, but I could not ls them out.

I looked at the man page of "pstree", it says,

Code:

Child threads  of a process are found under the parent process and are shown with the process name in curly braces, e.g.

           icecast2---13*[{icecast2}]

So, what does all this mean? Does it mean that 7735, 7736, 7737, 7743 are just threads but not processes? If so, why could I cd to /proc/<id> but not see them in "ps -elf".

Would somebody please help me?

Thanks!

whho

Hi, I know that it is possible to get the last background pid using the $! command, however when I use it in my QT application I got a wrong result. Below follows an example where this procedure works
Code:

[linux@localhost ~]$ (sleep 6 && echo "A test") &
[1] 3312
[linux@localhost ~]$ echo $!
3312
[linux@localhost ~]$ A test

Now my Qt application, where I got a wrong result:
Code:

./dbsync &>/dev/null &
[1] 5047
[linux@localhost comm5]$ echo $!
5047

but using the ps command it is possible to verify that the pid related to the right process is not the 5047 but 5050.
Generally it is the process that comes with the command Code:

echo $!

added of two.

I use QCoreApplication in my program. I do not know if it has something to do with this error.

Any advice is welcome

I have searched and was unsuccessful in finding a quick command or example to use.

I'm looking to automate an update process using command line in Debian.
Normally I'd use apt-get update|upgrade|dist-upgrade .

If apt-get finds a package to update it queries a Y/n response.
My objective is to have a script determine if this prompt is there, and if so to respond with 'Y'.
If not then it should not enter a response.

I know I'll need to use an IF/ELSE function, but what I'm having difficulties locating is to read the output of apt-get .

I know there's books and sites available, but they are all long and sometimes difficult to read or understand. And maybe my keywords are the right ones to use, as I'm not able to pinpoint a solution.

Thanks for your assistance.