8281274: deal with ActiveProcessorCount in os::Linux::print_container…

…_info

Backport-of: bb2e10ccea0c0b89b06ace034c99253e9999ec47

src/hotspot/os/linux/os_linux.cpp

@@ -2174,7 +2174,11 @@ bool os::Linux::print_container_info(outputStream* st) {
   int i = OSContainer::active_processor_count();
   st->print("active_processor_count: ");
   if (i > 0) {
-    st->print_cr("%d", i);
+    if (ActiveProcessorCount > 0) {
+      st->print_cr("%d, but overridden by -XX:ActiveProcessorCount %d", i, ActiveProcessorCount);
+    } else {
+      st->print_cr("%d", i);
+    }
   } else {
     st->print_cr("not supported");
   }

test/hotspot/jtreg/containers/docker/TestMisc.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -56,6 +56,7 @@ public static void main(String[] args) throws Exception {
             testMinusContainerSupport();
             testIsContainerized();
             testPrintContainerInfo();
+            testPrintContainerInfoActiveProcessorCount();
         } finally {
             DockerTestUtils.removeDockerImage(imageName);
         }
@@ -92,6 +93,15 @@ private static void testPrintContainerInfo() throws Exception {
         checkContainerInfo(Common.run(opts));
     }
 
+    private static void testPrintContainerInfoActiveProcessorCount() throws Exception {
+        Common.logNewTestCase("Test print_container_info()");
+
+        DockerRunOptions opts = Common.newOpts(imageName, "PrintContainerInfo").addJavaOpts("-XX:ActiveProcessorCount=2");
+        Common.addWhiteBoxOpts(opts);
+
+        OutputAnalyzer out = Common.run(opts);
+        out.shouldContain("but overridden by -XX:ActiveProcessorCount 2");
+    }
 
     private static void checkContainerInfo(OutputAnalyzer out) throws Exception {
         String[] expectedToContain = new String[] {