Sets recommended max Xmx 32G when set_recommended_max_xmx experiment …

…is enabled (#28442)

* Sets recommended max Xmx 32G when set_recommended_max_xmx experiment is enabled

* Fixing lint errors

* Adding comment to reason why 32G is recomemnded value

sdks/java/container/boot.go

@@ -159,8 +159,9 @@ func main() {
  cp = append(cp, filepath.Join(dir, filepath.FromSlash(name)))
  }
 
+ var setRecommendedMaxXmx = strings.Contains(options, "set_recommended_max_xmx")
  args := []string{
- "-Xmx" + strconv.FormatUint(heapSizeLimit(info), 10),
+ "-Xmx" + strconv.FormatUint(heapSizeLimit(info, setRecommendedMaxXmx), 10),
  // ParallelGC the most adequate for high throughput and lower CPU utilization
  // It is the default GC in Java 8, but not on newer versions
  "-XX:+UseParallelGC",
@@ -266,9 +267,14 @@ func makePipelineOptionsFile(options string) error {
 // it returns 70% of the physical memory on the machine. If it cannot determine
 // that value, it returns 1GB. This is an imperfect heuristic. It aims to
 // ensure there is memory for non-heap use and other overhead, while also not
-// underutilizing the machine.
-func heapSizeLimit(info *fnpb.ProvisionInfo) uint64 {
- if size, err := syscallx.PhysicalMemorySize(); err == nil {
+// underutilizing the machine. if set_recommended_max_xmx experiment is enabled, 
+// sets xmx to 32G. Under 32G JVM enables CompressedOops. CompressedOops 
+// utilizes memory more efficiently, and has positive impact on GC performance 
+// and cache hit rate.
+func heapSizeLimit(info *fnpb.ProvisionInfo, setRecommendedMaxXmx bool) uint64 {
+ if setRecommendedMaxXmx {
+ return 32 << 30
+ } else if size, err := syscallx.PhysicalMemorySize(); err == nil {
  return (size * 70) / 100
  }
  return 1 << 30