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23 
24 package gc.arguments;
25 
26 /*
27  * @test TestSelectDefaultGC
28  * @summary Test selection of GC when no GC option is specified
29  * @bug 8068582
30  * @key gc
31  * @library /test/lib
32  * @library /
33  * @requires vm.gc.Serial & vm.gc.G1
34  * @modules java.base/jdk.internal.misc
35  *          java.management
36  * @run driver gc.arguments.TestSelectDefaultGC
37  */
38 
39 import jdk.test.lib.process.OutputAnalyzer;
40 import jdk.test.lib.process.ProcessTools;
41 
42 public class TestSelectDefaultGC {
assertVMOption(OutputAnalyzer output, String option, boolean value)43     public static void assertVMOption(OutputAnalyzer output, String option, boolean value) {
44         output.shouldMatch(" " + option + " .*=.* " + value + " ");
45     }
46 
testDefaultGC(boolean actAsServer)47     public static void testDefaultGC(boolean actAsServer) throws Exception {
48         String[] args = new String[] {
49           "-XX:" + (actAsServer ? "+" : "-") + "AlwaysActAsServerClassMachine",
50           "-XX:" + (actAsServer ? "-" : "+") + "NeverActAsServerClassMachine",
51           "-XX:+PrintFlagsFinal",
52           "-version"
53         };
54 
55         // Start VM without specifying GC
56         ProcessBuilder pb = GCArguments.createJavaProcessBuilder(args);
57         OutputAnalyzer output = new OutputAnalyzer(pb.start());
58         output.shouldHaveExitValue(0);
59 
60         final boolean isServer = actAsServer;
61 
62         // Verify GC selection
63         // G1 is default for server class machines
64         assertVMOption(output, "UseG1GC",            isServer);
65         // Serial is default for non-server class machines
66         assertVMOption(output, "UseSerialGC",        !isServer);
67     }
68 
main(String[] args)69     public static void main(String[] args) throws Exception {
70         // Test server class machine
71         testDefaultGC(false);
72 
73         // Test non-server class machine
74         testDefaultGC(true);
75     }
76 }
77