COBOL MULTITHREADING - Quick Reference

1
2
3
4
5
6
7
8
9
* Thread creation syntax (conceptual)
THREAD START thread-name
    USING parameter1, parameter2
    RETURNING thread-handle.
 
* Thread procedure
THREAD-PROCEDURE.
    * Thread execution logic
    EXIT THREAD.

1
2
3
4
5
6
7
8
9
10
11
* Critical section protection
LOCK shared-resource
    * Protected code section
    PERFORM PROCESS-SHARED-DATA
UNLOCK shared-resource.
 
* Thread waiting
WAIT FOR thread-completion.
 
* Thread termination
THREAD STOP thread-handle.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
* Main program
PROCEDURE DIVISION.
MAIN-PROCESS.
    * Start multiple threads for file processing
    THREAD START FILE-PROCESSOR-1
        USING "FILE1.DAT"
        RETURNING thread1-handle.
    
    THREAD START FILE-PROCESSOR-2
        USING "FILE2.DAT"
        RETURNING thread2-handle.
    
    * Wait for both threads to complete
    WAIT FOR thread1-completion.
    WAIT FOR thread2-completion.
    
    DISPLAY "All files processed successfully."
    STOP RUN.
 
* Thread procedure for file processing
THREAD-PROCEDURE FILE-PROCESSOR.
    USING file-name.
    * File processing logic
    OPEN INPUT file-name
    * ... process file ...
    CLOSE file-name
    EXIT THREAD.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
* Shared data structure
01  SHARED-COUNTER PIC 9(6) VALUE ZERO.
01  COUNTER-LOCK PIC X VALUE "N".
 
* Thread-safe counter increment
PROCEDURE DIVISION.
INCREMENT-COUNTER.
    LOCK COUNTER-LOCK
        ADD 1 TO SHARED-COUNTER
    UNLOCK COUNTER-LOCK.
    EXIT THREAD.
 
* Multiple threads incrementing counter
THREAD START INCREMENTER-1
    RETURNING thread1-handle.
THREAD START INCREMENTER-2
    RETURNING thread2-handle.
WAIT FOR thread1-completion.
WAIT FOR thread2-completion.