src/share/vm/runtime/arguments.cpp

*** 2033,2046 ****
  
  // Use static initialization to get the default before parsing
  static const size_t DefaultHeapBaseMinAddress = HeapBaseMinAddress;
  
  void Arguments::set_heap_size() {
!   const julong phys_mem =
      FLAG_IS_DEFAULT(MaxRAM) ? MIN2(os::physical_memory(), (julong)MaxRAM)
                              : (julong)MaxRAM;
  
    // If the maximum heap size has not been set with -Xmx,
    // then set it as fraction of the size of physical memory,
    // respecting the maximum and minimum sizes of the heap.
    if (FLAG_IS_DEFAULT(MaxHeapSize)) {
      julong reasonable_max = phys_mem / MaxRAMFraction;
--- 2033,2072 ----
  
  // Use static initialization to get the default before parsing
  static const size_t DefaultHeapBaseMinAddress = HeapBaseMinAddress;
  
  void Arguments::set_heap_size() {
!   julong phys_mem =
      FLAG_IS_DEFAULT(MaxRAM) ? MIN2(os::physical_memory(), (julong)MaxRAM)
                              : (julong)MaxRAM;
  
+   // Experimental support for CGroup memory limits
+   if (UseCGroupMemoryLimitForHeap) {
+     // This is a rough indicator that a CGroup limit may be in force
+     // for this process
+     const char* lim_file = "/sys/fs/cgroup/memory/memory.limit_in_bytes";
+     FILE *fp = fopen(lim_file, "r");
+     if (fp != NULL) {
+       julong cgroup_max = 0;
+       int ret = fscanf(fp, JULONG_FORMAT, &cgroup_max);
+       if (ret == 1 && cgroup_max > 0) {
+         // If unlimited, cgroup_max will be a very large, but unspecified
+         // value, so use initial phys_mem as a limit
+         log_info(gc, heap)("Setting phys_mem to the min of cgroup limit ("
+                            JULONG_FORMAT "MB) and initial phys_mem ("
+                            JULONG_FORMAT "MB)", cgroup_max/M, phys_mem/M);
+         phys_mem = MIN2(cgroup_max, phys_mem);
+       } else {
+         warning("Unable to read/parse cgroup memory limit from %s: %s",
+                 lim_file, errno != 0 ? strerror(errno) : "unknown error");
+       }
+       fclose(fp);
+     } else {
+       warning("Unable to open cgroup memory limit file %s (%s)", lim_file, strerror(errno));
+     }
+   }
+ 
    // If the maximum heap size has not been set with -Xmx,
    // then set it as fraction of the size of physical memory,
    // respecting the maximum and minimum sizes of the heap.
    if (FLAG_IS_DEFAULT(MaxHeapSize)) {
      julong reasonable_max = phys_mem / MaxRAMFraction;