[Support] Run out of Memory A lot? {1.12}

Well I don't know about those kind of things. If you have a specific need like that then go for it, but ultimately the way java works, when you have a large heap (which is what these memory settings control), it makes the system "pause" longer to scan the entire thing looking for memory to free.

Pauses are what causes noticable lag just as much as slow code. I've done extensive work on EMC fine tuning the garbage collection process and actually lowered max memory before.

Ultimately here is our final settings:

Code:

// I've added notes on why they make sense to use.
// Many found on this thread: http://www.spigotmc.org/threads/server-launch-sh.35/ by other
// Large and experienced server owners.
// Also see official Oracle JVM Tuning section: www.oracle.com/technetwork/java/tuning-139912.html#section4.2.6
$baseOptions = ''
        . ' -Dfile.encoding=UTF-8' // Ensure files save as UTF8. Things break without this. See: EMC-261
        // == GC Tuning ==
        // This is low pause, keep server from ever spiking.
        // Very good details on why this is beneficial for MC: http://www.oracle.com/technetwork/java/gc-tuning-5-138395.html#0.0.0.%20The%20Concurrent%20Low%20Pause%20Collector|outline
        .' -XX:+UseConcMarkSweepGC -XX:+UseParNewGC'
        // Enable I-CMS, optimizing pauses and distrbutes GC over longer period so TPS keeps stable
        .' -XX:+CMSIncrementalMode -XX:+CMSIncrementalPacing'
        //Uses more CPU but we have unused cores. So this is beneficial to keep TPS affect low.
        .' -XX:+CMSParallelRemarkEnabled' // Use multiple threads for CMS Sweeps
        //. ' -XX:+UseG1GC' // G1GC try it out
        . ' -XX:MaxGCPauseMillis=20' // Ensure never more than 1 TPS lost
        . ' -XX:+DisableExplicitGC' // Prevent plugins causing GC
        // == Misc Tweaks==
        . ' -XX:+AggressiveOpts' // Enables soon-to-be-default optimizations.
        . ' -XX:+UseFastAccessorMethods' // Optimizes getters... pretty respectable deal.
        . ' -XX:+UseBiasedLocking' // Enables a technique for improving the performance of uncontended synchronization.
        // Bukkit synchronizes things for safety that is never contended under ideal cases. This
        // Optimizes those cases, so that uncontended syncs are much cheaper.
        // == Memory Management ==
        . ' -XX:TargetSurvivorRatio=90  ' // Use the survivor area more effeciently.
        //. ' -verbose:gc '
        . ' -Xloggc:gc.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+PrintGCTimeStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=128K ' // Log the GC to file
        .' -XX:LargePageSizeInBytes=2M  -XX:+UseLargePages ' // The biggest gain, but we need to configure system to use it
;
$gameOptions = $baseOptions . ' -Xmx9G -Xms5G'; // Give servers plenty of memory
$bungeeOptions = $baseOptions . ' -Denvironment=production -Xms2G -Xmx4g -DIReallyKnowWhatIAmDoingISwear=1';

I noticed OP has mojangs -XX+UseConcMarkSweepGC removed. It's EXTREMELY important to keep that or use G1GC at least.
So your games arguments should be like

Code:

-Xmx4G -XX:+UseG1GC

at the shortest.
G1GC and ConcMarkSweep are something you choose one of (dont use both!!) and in my testing they are extremely close in benefits, but we settled on the older fashioned CMS for now.
Mojang has defaulted CMS in the games profile, so if you removed it, you should add it back.
DO NOT leave it up to Java to use default. Default is bad for MC.

you didn't fix the ConcMarkSweep issue.