No blocking acquire on event loop

client/src/test/java/org/asynchttpclient/netty/channel/SemaphoreTest.java

@@ -215,6 +215,35 @@ private void nonBlockingFailsFast(ConnectionSemaphore semaphore) throws IOExcept
  semaphore.acquireChannelLock(PK, true); // must not throw
  }
 
+ @Test
+ @Timeout(unit = TimeUnit.MILLISECONDS, value = 1000)
+ public void combinedNonBlockingReleasesGlobalPermitWhenPerHostExhausted() throws IOException {
+ // global(2) > per-host(1): the non-blocking acquire takes a global permit, then fails on the
+ // per-host limit. It must release the global permit it just took (releaseGlobal); otherwise a
+ // request to a DIFFERENT host would be wrongly starved of the still-held global permit. With
+ // global == per-host (as in the fail-fast tests above) the acquire fails on the global limit first
+ // and this release branch is never exercised, so use a wider global limit to reach it.
+ CombinedConnectionSemaphore semaphore = new CombinedConnectionSemaphore(2, 1, NON_BLOCKING__LONG_TIMEOUT);
+ Object hostA = new Object();
+ Object hostB = new Object();
+
+ semaphore.acquireChannelLock(hostA); // global -> 1 free, per-host(A) -> 0
+
+ // The non-blocking acquire for hostA must be rejected by the PER-HOST limit (a global permit was
+ // still free), confirming it got past the global gate and into the releaseGlobal branch.
+ boolean perHostRejected = false;
+ try {
+ semaphore.acquireChannelLock(hostA, true);
+ } catch (TooManyConnectionsPerHostException e) {
+ perHostRejected = true;
+ }
+ assertTrue(perHostRejected, "second hostA acquire must be rejected by the per-host limit, not the global one");
+
+ // If the global permit taken during that failed attempt had leaked, 0 global permits would remain
+ // and this different-host acquire would wrongly throw. It must succeed, proving releaseGlobal ran.
+ semaphore.acquireChannelLock(hostB, true); // must not throw
+ }
+
  @Test
  @Timeout(unit = TimeUnit.MILLISECONDS, value = 1000)
  public void defaultNonBlockingOverloadDelegatesToBlockingAcquire() throws IOException {