[转]java.lang.OutOfMemoryError：GC overhead limit exceeded

  1 bool print_gc_overhead_limit_would_be_exceeded = false;
  2 
  3 if (is_full_gc) {
  4 
  5   if (gc_cost() > gc_cost_limit &&
  6 
  7     free_in_old_gen < (size_t) mem_free_old_limit &&
  8 
  9     free_in_eden < (size_t) mem_free_eden_limit) {
 10 
 11     // Collections, on average, are taking too much time, and
 12 
 13     //      gc_cost() > gc_cost_limit
 14 
 15     // we have too little space available after a full gc.
 16 
 17     //      total_free_limit < mem_free_limit
 18 
 19     // where
 20 
 21     //   total_free_limit is the free space available in
 22 
 23     //     both generations
 24 
 25     //   total_mem is the total space available for allocation
 26 
 27     //     in both generations (survivor spaces are not included
 28 
 29     //     just as they are not included in eden_limit).
 30 
 31     //   mem_free_limit is a fraction of total_mem judged to be an
 32 
 33     //     acceptable amount that is still unused.
 34 
 35     // The heap can ask for the value of this variable when deciding
 36 
 37     // whether to thrown an OutOfMemory error.
 38 
 39     // Note that the gc time limit test only works for the collections
 40 
 41     // of the young gen + tenured gen and not for collections of the
 42 
 43     // permanent gen.  That is because the calculation of the space
 44 
 45     // freed by the collection is the free space in the young gen +
 46 
 47     // tenured gen.
 48 
 49     // At this point the GC overhead limit is being exceeded.
 50 
 51     inc_gc_overhead_limit_count();
 52 
 53     if (UseGCOverheadLimit) {
 54 
 55       if (gc_overhead_limit_count() >=
 56 
 57           AdaptiveSizePolicyGCTimeLimitThreshold){
 58 
 59         // All conditions have been met for throwing an out-of-memory
 60 
 61         set_gc_overhead_limit_exceeded(true);
 62 
 63         // Avoid consecutive OOM due to the gc time limit by resetting
 64 
 65         // the counter.
 66 
 67         reset_gc_overhead_limit_count();
 68 
 69       } else {
 70 
 71         // The required consecutive collections which exceed the
 72 
 73         // GC time limit may or may not have been reached. We
 74 
 75         // are approaching that condition and so as not to
 76 
 77         // throw an out-of-memory before all SoftRef‘s have been
 78 
 79         // cleared, set _should_clear_all_soft_refs in CollectorPolicy.
 80 
 81         // The clearing will be done on the next GC.
 82 
 83         bool near_limit = gc_overhead_limit_near();
 84 
 85         if (near_limit) {
 86 
 87           collector_policy->set_should_clear_all_soft_refs(true);
 88 
 89           if (PrintGCDetails && Verbose) {
 90 
 91             gclog_or_tty->print_cr("  Nearing GC overhead limit, "
 92 
 93               "will be clearing all SoftReference");
 94 
 95           }
 96 
 97         }
 98 
 99       }
100 
101     }
102 
103     // Set this even when the overhead limit will not
104 
105     // cause an out-of-memory.  Diagnostic message indicating
106 
107     // that the overhead limit is being exceeded is sometimes
108 
109     // printed.
110 
111     print_gc_overhead_limit_would_be_exceeded = true;
112 
113  
114 
115   } else {
116 
117     // Did not exceed overhead limits
118 
119     reset_gc_overhead_limit_count();
120 
121   }
122 
123 }