### Get the pid of the relevant batch.
$ ps -aux | grep java
top command to monitor CPU and memory information (the target in the example is pid: 3067)
$top -p 3067
For All Process
① 3872540 total > All physical memory(約3.8GB)
② 4190204 total > Memory in the swap space(約4.1GB)
③ 1562088 free > empty space (約0.15GB)
④ 2406996 used > Memory used by all (batch) processes on the server.(約2.4GB)
⑤ 1308640 > Buffer/cache area memory allocated by the OS(約1.3GB)
The formula is
TOTAL(①) = free(③) + used(④) + buff/cache(⑤)
For Each pid Process
Column for each PID: Memory allocated for each PID
VIRT: amount of virtual memory: ex) 3136304 (約3.1GB)
RES : physical memory ex) 316760 (約0.31GB)
%CPU: used CPU(%) (約0.0%)
The formula is
%MEM(約8.2%) = Amount of physical memory allocated to pid: 23819 (約0.31GB) / All physical memory(約3.8GB)
Check the actual used memory by JSTAT command.
$ jstat -gc 46702
Automatically execute commands one second at a time with the watch command.
$ watch -n 1 jstat -gc 46702
Check the used space.
（709[S0U] + 0.0[S1U] + 11459.1[EU] +41758.9[OU]） / 1024 = 52.66MB ...*1
*1: 52.66MB is much lower than allocated to this pid (約0.31GB). This is thought to be Java application is allocating the enough memory as a buffer space
Ref: https://qiita.com/kaikusakari/items/9b7c3d1fb524eb6aa348
Result of Migration test on batch
While file(about 10000 lines at each file) is continuously sent to server and batch is processing...
%CPU is roughly 50%.
If large amounts of data are linked in other batches at the same time, delays may occur, but if large amounts of data are linked in a single batch, there is no problem.
%VIRTUAL MEMORY is same as normal(8.2%)
Memory while file processing do not exceed the amount of allocated memory by java application.
Real used memory is about 100 MB while batch is processing.