Concurrency Coordination Reports

Semaphore Capacity Coordination Report

Grant requests against a fixed permit pool and report the remaining capacity.

semaphore A `Semaphore` hands out a bounded number of permits, so the permits still available describe how much shared capacity remains.

Semaphore Capacity Coordination Report

requests
SemaphoreCapacityCoordinationReport.java
Replay: real traced execution (multi-file project)
import java.util.concurrent.Semaphore;

public class SemaphoreCapacityCoordinationReport {
    public static void main(String[] args) {
        int requests = 2;
        Semaphore permits = new Semaphore(3);
        int granted = 0;

        for (int i = 0; i < requests; i++) {
            if (permits.tryAcquire()) {
                granted++;
            }
        }

        int available = permits.availablePermits();
        String status = available == 0 ? "full" : available <= 1 ? "tight" : "open";

        System.out.println("requests=" + requests + " granted=" + granted + " available=" + available + " status=" + status);
    }
}

import java.util.concurrent.Semaphore;

public class SemaphoreCapacityCoordinationReport {
    public static void main(String[] args) {
        int requests = 0;
        Semaphore permits = new Semaphore(3);
        int granted = 0;

        for (int i = 0; i < requests; i++) {
            if (permits.tryAcquire()) {
                granted++;
            }
        }

        int available = permits.availablePermits();
        String status = available == 0 ? "full" : available <= 1 ? "tight" : "open";

        System.out.println("requests=" + requests + " granted=" + granted + " available=" + available + " status=" + status);
    }
}

import java.util.concurrent.Semaphore;

public class SemaphoreCapacityCoordinationReport {
    public static void main(String[] args) {
        int requests = 3;
        Semaphore permits = new Semaphore(3);
        int granted = 0;

        for (int i = 0; i < requests; i++) {
            if (permits.tryAcquire()) {
                granted++;
            }
        }

        int available = permits.availablePermits();
        String status = available == 0 ? "full" : available <= 1 ? "tight" : "open";

        System.out.println("requests=" + requests + " granted=" + granted + " available=" + available + " status=" + status);
    }
}

  1. requests ← 2, granted ← 0

    3public class SemaphoreCapacityCoordinationReport {4    public static void main(String[] args) {5        int requests→ 2 = 2;  //@requests=0, 36        Semaphore permits = new Semaphore(3);7        int granted→ 0 = 0;

  2. for (int i = 0; i < requests; i++)

    pass 1 of 2
    9for (int i0 = 0; i < requests2; i++) {10    if (permits.tryAcquire()) {

  3. granted ← 1

    pass 1 of 2
    9for (int i = 0; i < requests; i++) {10    if (permits.tryAcquire()) {11        granted→ 1++;12    }

  4. for (int i = 0; i < requests; i++)

    pass 2 of 2
    9for (int i1 = 0; i < requests2; i++) {10    if (permits.tryAcquire()) {

  5. granted ← 2

    pass 2 of 2
    9for (int i = 0; i < requests; i++) {10    if (permits.tryAcquire()) {11        granted→ 2++;12    }

  6. available ← 1, status ← tight

    15    int available→ 1 = permits.availablePermits();16    String status→ tight = available1 == 0 ? "full" : available <= 1 ? "tight" : "open";1718    System.out.println("requests=" + requests2 + " granted=" + granted2 + " available=" + available1 + " status=" + statustight);19}
    outputrequests=2 granted=2 available=1 status=tight

  1. requests ← 0, granted ← 0, available ← 3, status ← open

    3public class SemaphoreCapacityCoordinationReport {4    public static void main(String[] args) {5        int requests→ 0 = 0;6        Semaphore permits = new Semaphore(3);7        int granted→ 0 = 0;89        for (int i = 0; i < requests; i++) {10            if (permits.tryAcquire()) {11                granted++;12            }13        }1415        int available→ 3 = permits.availablePermits();16        String status→ open = available3 == 0 ? "full" : available <= 1 ? "tight" : "open";1718        System.out.println("requests=" + requests0 + " granted=" + granted0 + " available=" + available3 + " status=" + statusopen);19    }
    outputrequests=0 granted=0 available=3 status=open

  1. requests ← 3, granted ← 0

    3public class SemaphoreCapacityCoordinationReport {4    public static void main(String[] args) {5        int requests→ 3 = 3;6        Semaphore permits = new Semaphore(3);7        int granted→ 0 = 0;

  2. for (int i = 0; i < requests; i++)

    pass 1 of 3
    9for (int i0 = 0; i < requests3; i++) {10    if (permits.tryAcquire()) {
    All 3 passes — pass 1 is the card above
    passi
    10
    21
    32

  3. granted ← 1

    pass 1 of 3
    9for (int i = 0; i < requests; i++) {10    if (permits.tryAcquire()) {11        granted→ 1++;12    }
    All 3 passes — pass 1 is the card above
    passgranted
    10 → 1
    21 → 2
    32 → 3

  4. available ← 0, status ← full

    15    int available→ 0 = permits.availablePermits();16    String status→ full = available0 == 0 ? "full" : available <= 1 ? "tight" : "open";1718    System.out.println("requests=" + requests3 + " granted=" + granted3 + " available=" + available0 + " status=" + statusfull);19}
    outputrequests=3 granted=3 available=0 status=full