What are the Linux memory management commands?

Linux memory management commands include: 1. [jmap] represents the Java memory imaging tool; 2. [jstat] represents the virtual machine statistics monitoring tool; 3. [YGC] represents the Minor from application startup to sampling Number of GCs; 4. [YGCT] represents the time taken by Minor GC from application startup to sampling.

Linux memory management commands are:

Check whether there is a memory leak

1. Java memory imaging tool: jmap

jmap -histo:live pid Outputs the memory histogram of the specified pid alive

The first column, the serial number, has no practical meaning

The second column, the number of object instances

The third column, the total memory occupied by object instances, unit: bytes

The fourth column, the object instance name

The last line, the total number of instances and total memory usage

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2. Virtual machine statistics Information monitoring tool: jstat

jstat -gcutil pid 10s records gc recycling information every 10s, such as:

  S0     S1     E      O      M     CCS    YGC     YGCT    FGC    FGCT     GCT   
  0.00  80.28  38.44   4.19  96.53  93.94  13805  709.977     5    1.078  711.055
  0.00  80.28  57.48   4.19  96.53  93.94  13805  709.977     5    1.078  711.055
  0.00  80.28  71.95   4.19  96.53  93.94  13805  709.977     5    1.078  711.055
  0.00  80.28  84.82   4.19  96.53  93.94  13805  709.977     5    1.078  711.055
 77.88   0.00   4.89   4.19  96.53  93.94  13806  710.049     5    1.078  711.127
 77.88   0.00  13.71   4.19  96.53  93.94  13806  710.049     5    1.078  711.127
 77.88   0.00  26.91   4.19  96.53  93.94  13806  710.049     5    1.078  711.127
  0.00  83.91   2.54   4.19  96.53  93.94  13807  710.080     5    1.078  711.158

• S0 Survivor0 Area usage rate

• S1 Survivor1 area usage rate

• E Eden area usage rate

• O (Old) represents the old generation usage rate

• M MetaspaceSize has been Percentage of current capacity used

• CCS Compression usage ratio

• P (Permanent) Represents the permanent generation usage rate

• YGC (Young GC) represents the number of Minor GCs from application startup to sampling

• #YGCT Represents the Minor GC time (unit seconds) from application startup to sampling time

• FGC (Full GC) represents the time from application The number of Full GC times from program startup to sampling

• FGCT (Full GC) represents the Full GC time taken from application startup to sampling (unit seconds)

• GCT Represents the total time taken by Minor & Full GC from application startup to sampling time (unit seconds)

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