Showing Available Heap Sizes

Table of Contents

Example 1: No JVMs have been started.
Example 2: An Azul Inspector 1GB JVM has been started.

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You can use zing-ps and awk commands to show available heap sizes in MB. The output of the zing-ps -acct command is in bytes; you might prefer to think in Megabytes.

This technique is based on the zing-ps –acct command and is a one-line script that uses the Linux grep command to search the output combined with the Linux awk command to calculate and format the output.

The output from the zing-ps –acct command is searched by grep for the line containing the Committed string. The awk command uses $3 to select the third field which is the available balance in column three of the output with the heading BALANCE.

The following one-line script prints the maximum Available Heap size for the JVM command option –Xmx and if other JVMs have already been started this is less than the maximum Reservable value in column four headed MAXIMUM.
```
 echo "Zing Available Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($3/(1024*1024))}'
```
To read the total Reservable value in MB, in this one-line script the awk command is modified to use $4 to select the fourth field which is the MAXIMUM balance

echo "Zing Total Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($4/(1024*1024))}

Example 1: No JVMs have been started.

 [root@localhost bin]# zing-ps --acct

 Fund breakdown (total 8)

                           NAME         BALANCE         MAXIMUM

    fund[0]:          Committed      4041211904      4041211904

    fund[1]:          Overdraft       222298112       222298112

    fund[2]:            Unknown               0               0

    fund[3]:    PausePrevention       222298112       222298112

    fund[4]:            Unknown               0               0

    fund[5]:            Unknown               0               0

    fund[6]:            Unknown               0               0

    fund[7]:            Unknown               0               0

Found 0 processes.

[root@localhost bin]# echo "Zing Available Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($3/(1024*1024))}'`

Zing Available Heapsize (MB) is 3854

[root@localhost bin]# echo "Zing Total Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($4/(1024*1024))}'`

Zing Total Heapsize (MB) is 3854

root        5785 java

                        NAME   BALANCE  ALLOCATED      MAXIMUM FND ODFND

account[0]:          default  10485760   2097152      12582912   0    1

account[1]:     emergency_gc         0         0             0  -1   -1

account[2]:             heap 555745280  505413632   1283457024   0    1

account[3]: pause_prevention         0          0 274877906944   3    3

account[4]:          unknown         0          0            0  -1   -1

account[5]:          unknown         0          0            0  -1   -1

account[6]:          unknown         0          0            0  -1   -1

account[7]:          unknown         0          0            0  -1   -1



[root@localhost bin]# echo "Zing Available Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($3/(1024*1024))}'`

Zing Available Heapsize (MB) is 2830

[root@localhost bin]# echo "Zing Total Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($4/(1024*1024))}'`

Zing Total Heapsize (MB) is 3854

Example 2: An Azul Inspector 1GB JVM has been started.

See Azul Systems website to download free Open Source tool Azul Inspector, at https://www.azul.com/products/open-source-tools/azul_inspector.

 [root@localhost bin]# zing-ps --acct

Fund breakdown (total 8)

                           NAME         BALANCE         MAXIMUM

    fund[0]:          Committed      2967470080      4041211904

    fund[1]:          Overdraft       222298112       222298112

    fund[2]:            Unknown               0               0

    fund[3]:    PausePrevention       222298112       222298112

    fund[4]:            Unknown               0               0

    fund[5]:            Unknown               0               0

    fund[6]:            Unknown               0               0

    fund[7]:            Unknown               0               0

Found 1 processes.

USER         PID PROCESS

root        5785 java

                        NAME   BALANCE  ALLOCATED      MAXIMUM FND ODFND

account[0]:          default  10485760   2097152      12582912   0    1

account[1]:     emergency_gc         0         0             0  -1   -1

account[2]:             heap 555745280  505413632   1283457024   0    1

account[3]: pause_prevention         0          0 274877906944   3    3

account[4]:          unknown         0          0            0  -1   -1

account[5]:          unknown         0          0            0  -1   -1

account[6]:          unknown         0          0            0  -1   -1

account[7]:          unknown         0          0            0  -1   -1



[root@localhost bin]# echo "Zing Available Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($3/(1024*1024))}'`

Zing Available Heapsize (MB) is 2830

[root@localhost bin]# echo "Zing Total Heapsize (MB) is "`zing-ps --acct|grep Committed|awk '{print int($4/(1024*1024))}'`

Zing Total Heapsize (MB) is 3854