jscanner

commit 1f7f1058d0b283b5ff92218e00caf9030edebe69
parent 945bf27e660d7076705fd532ee5a604f4f7f81d6
Author: Matthias Jaros <jaros@mailbox.org>
Date:   Mon, 16 Mar 2026 12:05:35 +0100

- Removed synchronized on PortRange class, because only called from one
thread only.
- Added max virtual thread worker cap to reduce memory consumption if
required. Therefore also moved progress update into virtual thread,
otherwise progress just gets updated at the end of a target host scan.

Diffstat:
M
src/main/java/com/it_jaros/networkScanner/PortRange.java
 | 
4
++--
M
src/main/java/com/it_jaros/networkScanner/Scanner.java
 | 
19
++++++++++++++-----

2 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/src/main/java/com/it_jaros/networkScanner/PortRange.java b/src/main/java/com/it_jaros/networkScanner/PortRange.java
@@ -65,7 +65,7 @@ public class PortRange {
         }
     }
 
-    public synchronized int next() {
+    public int next() {
         int p = availablePorts.nextSetBit(cursor);
         if (p > 0) {
             availablePorts.clear(p);
@@ -77,7 +77,7 @@ public class PortRange {
         throw new NoSuchElementException("Reached end of port range");
     }
 
-    public synchronized boolean hasNext() {
+    public boolean hasNext() {
         return availablePorts.nextSetBit(cursor) > 0;
     }
 
diff --git a/src/main/java/com/it_jaros/networkScanner/Scanner.java b/src/main/java/com/it_jaros/networkScanner/Scanner.java
@@ -22,6 +22,7 @@ public class Scanner {
 
     private final Counter counter = new Counter();
     private final ProgressBar progressBar = new ProgressBar();
+    private final Semaphore maxWorkers = new Semaphore(100000);
     private final Semaphore socketLimit;
     private final int timeoutInMillis;
     private final long delayInNanos;
@@ -70,10 +71,20 @@ public class Scanner {
         try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor();) {
             List<Future<Integer>> futures = new ArrayList<>();
             while (portRange.hasNext()) {
+                maxWorkers.acquireUninterruptibly();
                 final int currentPort = portRange.next();
                 futures.add(executor.submit(() -> {
-                    waitForSlot(portSlotFactory);
-                    return scanPort(target, currentPort);
+                    try {
+                        waitForSlot(portSlotFactory);
+                        int port = scanPort(target, currentPort);
+                        if (port != -1) {
+                            progress.open().incrementAndGet();
+                        }
+                        return port;
+                    } finally {
+                        maxWorkers.release();
+                        progress.done().incrementAndGet();
+                    }
                 }));
             }
 
@@ -81,13 +92,11 @@ public class Scanner {
                 try {
                     int port = f.get();
                     if (port != -1) {
+                        // openPorts is not threadsafe, so we do not update it outside the worker threads
                         openPorts.set(port);
-                        progress.open().incrementAndGet();
                     }
                 } catch (InterruptedException | ExecutionException e) {
                     e.printStackTrace();
-                } finally {
-                    progress.done().incrementAndGet();
                 }
             });
         }