Overview

Odd-Even Sort, also known as Brick Sort, is a relatively simple sorting algorithm, inspired by the Bubble Sort algorithm. It operates by concurrently comparing and swapping adjacent pairs of elements in the array to sort the values. The algorithm gets its name from the way it partitions the sorting operation into two phases.

For parallel or multithreaded implementations, the concurrent nature of the Odd-Even Sort becomes especially prominent. Given its inherently parallel structure, multiple pairs can be compared and potentially swapped simultaneously. This makes Odd-Even Sort an interesting choice for parallel computing environments, albeit it's not the most efficient sorting algorithm for larger datasets.

Each of these codes including pseudocode utilizes multithreading to perform odd-even sort. Note that depending on the length of the array and the nature of the data, multithreading might not always give a performance boost due to overheads associated with thread management. The benefits become more apparent with larger datasets.

Pseudocode

DEFINE array with elements [100, 8, 100, 26, 4, 8, 66, 37, 98, 23, 83, 58, 99, 78, 73, 93, 68, 8, 16, 29]
SET NUM_THREADS to 4

INITIALIZE barrier for NUM_THREADS

STRUCTURE ThreadParams WITH
    INTEGER threadId

FUNCTION ThreadSort(ARGUMENTS arg AS POINTER TO ThreadParams) RETURNS NOTHING
    SET threadId to arg->threadId
    SET n to size of array
    FOR phase from 0 to n - 1 DO
        SET begin to (threadId if threadId MOD 2 equals phase MOD 2 else threadId + 1)
        FOR i from begin to n - 2 by NUM_THREADS STEPS DO
            IF array[i] > array[i + 1] THEN
                SWAP array[i] with array[i + 1]
            ENDIF
        ENDFOR
        BARRIER WAIT
    ENDFOR
    RETURN NOTHING
ENDFUNCTION

FUNCTION main() RETURNS INTEGER
    INITIALIZE threads[NUM_THREADS] for storing thread identifiers
    INITIALIZE params[NUM_THREADS] for storing thread parameters

    FOR i from 0 to NUM_THREADS - 1 DO
        SET params[i].threadId to i
        CREATE THREAD with ThreadSort function and params[i] as arguments
        STORE THREAD ID in threads[i]
    ENDFOR

    FOR i from 0 to NUM_THREADS - 1 DO
        JOIN threads[i]
    ENDFOR

    DESTROY barrier

    PRINT "Sorted Array: "
    FOR EACH element IN array DO
        PRINT element
    ENDFOR

    RETURN 0
ENDFUNCTION