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  1. JDK
  2. JDK-8265326

Strange Characters in G1GC GC Log

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    Details

    • Subcomponent:
      gc
    • Introduced In Build:
      b18
    • Introduced In Version:
      16
    • Resolved In Build:
      b20
    • CPU:
      x86_64
    • OS:
      os_x

      Description

      ADDITIONAL SYSTEM INFORMATION :
      Mac OS X 10.15.7
      Happens in both Java 16 and 17-ea

      openjdk version "16" 2021-03-16
      OpenJDK Runtime Environment (build 16+36-2231)
      OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing)

      openjdk version "17-ea" 2021-09-14
      OpenJDK Runtime Environment (build 17-ea+13-1000)
      OpenJDK 64-Bit Server VM (build 17-ea+13-1000, mixed mode, sharing)

      A DESCRIPTION OF THE PROBLEM :
      When generating a G1 GC log, strange characters appear in the GC log, making parsing difficult.

      REGRESSION : Last worked in version 15.0.2

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Generate a GC Log with G1, either with -verbose:gc or -Xlog:gc:log.vgc


      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      java -showversion -verbose:gc G1Characters
      [0.005s][info][gc] Using G1
      openjdk version "15.0.2" 2021-01-19
      OpenJDK Runtime Environment Zulu15.29+15-CA (build 15.0.2+7)
      OpenJDK 64-Bit Server VM Zulu15.29+15-CA (build 15.0.2+7, mixed mode, sharing)
      [0.136s][info][gc] GC(0) Pause Young (Concurrent Start) (G1 Humongous Allocation) 457M->24M(1040M) 2.574ms
      [0.136s][info][gc] GC(1) Concurrent Cycle
      [0.142s][info][gc] GC(1) Pause Remark 72M->72M(296M) 3.834ms
      [0.143s][info][gc] GC(1) Pause Cleanup 88M->88M(296M) 0.120ms
      [0.144s][info][gc] GC(1) Concurrent Cycle 7.757ms
      [0.145s][info][gc] GC(2) Pause Young (Concurrent Start) (G1 Humongous Allocation) 120M->24M(296M) 1.392ms
      [0.145s][info][gc] GC(3) Concurrent Cycle
      [0.147s][info][gc] GC(3) Pause Remark 72M->72M(296M) 0.224ms
      [0.147s][info][gc] GC(3) Pause Cleanup 88M->88M(296M) 0.035ms
      [0.149s][info][gc] GC(3) Concurrent Cycle 3.256ms
      [0.150s][info][gc] GC(4) Pause Young (Concurrent Start) (G1 Humongous Allocation) 136M->24M(296M) 0.698ms
      [0.150s][info][gc] GC(5) Concurrent Cycle
      [0.151s][info][gc] GC(5) Pause Remark 72M->72M(296M) 0.202ms
      [0.152s][info][gc] GC(5) Pause Cleanup 88M->88M(296M) 0.027ms
      [0.152s][info][gc] GC(5) Concurrent Cycle 2.374ms
      etc.
      ACTUAL -
      java -showversion -verbose:gc G1Characters
      [0.004s][info][gc] Using G1
      openjdk version "16" 2021-03-16
      OpenJDK Runtime Environment (build 16+36-2231)
      OpenJDK 64-Bit Server VM (build 16+36-2231, mixed mode, sharing)
      [0.134s][info][gc] GC(0) Pause Young (Concurrent Start) (G1 Humongous Allocation) 457M->24M(1040M) 3.213ms
      [0.134s][info][gc] GC(1) Concurrent Undo Cycle
      [0.140s][info][gc] GC(1) ???t? 5.650ms
      [0.151s][info][gc] GC(2) Pause Young (Concurrent Start) (G1 Humongous Allocation) 456M->24M(1040M) 1.674ms
      [0.151s][info][gc] GC(3) Concurrent Undo Cycle
      [0.153s][info][gc] GC(3) ???t? 2.388ms
      [0.164s][info][gc] GC(4) Pause Young (Concurrent Start) (G1 Humongous Allocation) 456M->24M(1040M) 1.139ms
      [0.164s][info][gc] GC(5) Concurrent Undo Cycle
      [0.166s][info][gc] GC(5) ???t? 1.973ms
      etc.

      ---------- BEGIN SOURCE ----------
      public class G1Characters {
        private static Object leak;
        public static void main(String... args) {
          while(true) {
            leak = new byte[10_000_000];
          }
        }
      }

      ---------- END SOURCE ----------

      CUSTOMER SUBMITTED WORKAROUND :
      Use a different version of Java or a different garbage collector

      FREQUENCY : always


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              Assignee:
              fmatte Fairoz Matte
              Reporter:
              webbuggrp Webbug Group
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                Created:
                Updated:
                Resolved: