docker memory consumption

[KonradHoeffner]

Using the current master branch, the docker container uses more than 500 MB of RAM even at the start when nothing is happening:

$ docker build -t lodview .
$ docker run --network=host --privileged -d lodview
$ docker stats
CONTAINER ID   NAME            CPU %     MEM USAGE / LIMIT     MEM %     NET I/O   BLOCK I/O     PIDS
413bd2f64fca   sweet_leavitt   0.00%     529.5MiB / 15.42GiB   3.35%     0B / 0B   57.6MB / 0B   36

Output of top from within the container:

top - 09:03:30 up 51 min,  0 users,  load average: 0.87, 0.95, 0.73
Tasks:   3 total,   1 running,   2 sleeping,   0 stopped,   0 zombie
%Cpu(s):  7.9 us,  2.1 sy,  0.0 ni, 89.8 id,  0.0 wa,  0.1 hi,  0.1 si,  0.0 st
MiB Mem :  15791.6 total,   7311.0 free,   3588.6 used,   4892.0 buff/cache
MiB Swap:  16384.0 total,  16384.0 free,      0.0 used.   9873.9 avail Mem 

    PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ COMMAND                                                                                                                                                                                                                                                
      1 root       1   0 8060128 536560  20060 S   0.3   3.3   0:13.90 java                                                                                                                                                                                                                                                   
     47 root       1   0    5756   3604   3108 S   0.0   0.0   0:00.08 bash                                                                                                                                                                                                                                                   
     59 root       1   0    9768   3368   2844 R   0.0   0.0   0:00.01 top 

# java -XX:+PrintFlagsFinal -version | grep -E "UseContainerSupport | InitialRAMPercentage | MaxRAMPercentage | MinRAMPercentage"
   double InitialRAMPercentage                      = 1.562500                            {product}
   double MaxRAMPercentage                          = 25.000000                           {product}
   double MinRAMPercentage                          = 50.000000                           {product}
     bool UseContainerSupport                       = true                                {product}

# jinfo 1 | grep "VM flags"
Non-default VM flags: -XX:CICompilerCount=4 -XX:InitialHeapSize=260046848 -XX:MaxHeapSize=4139778048 -XX:MaxNewSize=1379926016 -XX:MinHeapDeltaBytes=524288 -XX:NewSize=86507520 -XX:OldSize=173539328 -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseFastUnorderedTimeStamps -XX:+UseParallelGC

Is there a way to reduce the usage?

[KonradHoeffner]

VisualVM

$ docker run --network=host --privileged -d -e CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.rmi.port=9090 -Dcom.sun.management.jmxremote=true -Dcom.sun.management.jmxremote.port=9090 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.local.only=false -Djava.rmi.server.hostname=localhost" lodview

Opening a few tabs at the same time:

• http://localhost:8080/lodview/Berlin.html
• http://localhost:8080/lodview/Moscow.html
• http://localhost:8080/lodview/Leipzig.html
• http://localhost:8080/lodview/Dresden.html

Heap

Garbage collection was manually performed at the end.

Serial garbage collector seems to be much better suited to minimize RAM usage.

docker run --network=host --privileged -e CATALINA_OPTS="$CATALINA_OPTS -Dcom.sun.management.jmxremote.rmi.port=9090 -Dcom.sun.management.jmxremote=true -Dcom.sun.management.jmxremote.port=9090 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.local.only=false -Djava.rmi.server.hostname=localhost -XX:+UseSerialGC" lodview

Opening the same tabs as before.

[KonradHoeffner]

Reduced somewhat by #55.