diff --git a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp index d1dd28ca2f30615800dd0746e5230d40b0e065d6..f717bd9226edf86c033bd76fc5db4c147914ced4 100644 --- a/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp +++ b/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp @@ -1044,29 +1044,56 @@ resize_if_necessary_after_full_collection(size_t word_size) { const size_t capacity_after_gc = capacity(); const size_t free_after_gc = capacity_after_gc - used_after_gc; + // This is enforced in arguments.cpp. + assert(MinHeapFreeRatio <= MaxHeapFreeRatio, + "otherwise the code below doesn't make sense"); + // We don't have floating point command-line arguments - const double minimum_free_percentage = (double) MinHeapFreeRatio / 100; + const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0; const double maximum_used_percentage = 1.0 - minimum_free_percentage; - const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100; + const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0; const double minimum_used_percentage = 1.0 - maximum_free_percentage; - size_t minimum_desired_capacity = (size_t) (used_after_gc / maximum_used_percentage); - size_t maximum_desired_capacity = (size_t) (used_after_gc / minimum_used_percentage); - - // Don't shrink less than the initial size. - minimum_desired_capacity = - MAX2(minimum_desired_capacity, - collector_policy()->initial_heap_byte_size()); - maximum_desired_capacity = - MAX2(maximum_desired_capacity, - collector_policy()->initial_heap_byte_size()); - - // We are failing here because minimum_desired_capacity is - assert(used_after_gc <= minimum_desired_capacity, "sanity check"); - assert(minimum_desired_capacity <= maximum_desired_capacity, "sanity check"); + const size_t min_heap_size = collector_policy()->min_heap_byte_size(); + const size_t max_heap_size = collector_policy()->max_heap_byte_size(); + + // We have to be careful here as these two calculations can overflow + // 32-bit size_t's. + double used_after_gc_d = (double) used_after_gc; + double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage; + double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage; + + // Let's make sure that they are both under the max heap size, which + // by default will make them fit into a size_t. + double desired_capacity_upper_bound = (double) max_heap_size; + minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d, + desired_capacity_upper_bound); + maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d, + desired_capacity_upper_bound); + + // We can now safely turn them into size_t's. + size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d; + size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d; + + // This assert only makes sense here, before we adjust them + // with respect to the min and max heap size. + assert(minimum_desired_capacity <= maximum_desired_capacity, + err_msg("minimum_desired_capacity = "SIZE_FORMAT", " + "maximum_desired_capacity = "SIZE_FORMAT, + minimum_desired_capacity, maximum_desired_capacity)); + + // Should not be greater than the heap max size. No need to adjust + // it with respect to the heap min size as it's a lower bound (i.e., + // we'll try to make the capacity larger than it, not smaller). + minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size); + // Should not be less than the heap min size. No need to adjust it + // with respect to the heap max size as it's an upper bound (i.e., + // we'll try to make the capacity smaller than it, not greater). + maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size); if (PrintGC && Verbose) { - const double free_percentage = ((double)free_after_gc) / capacity(); + const double free_percentage = + (double) free_after_gc / (double) capacity_after_gc; gclog_or_tty->print_cr("Computing new size after full GC "); gclog_or_tty->print_cr(" " " minimum_free_percentage: %6.2f", @@ -1078,45 +1105,47 @@ resize_if_necessary_after_full_collection(size_t word_size) { " capacity: %6.1fK" " minimum_desired_capacity: %6.1fK" " maximum_desired_capacity: %6.1fK", - capacity() / (double) K, - minimum_desired_capacity / (double) K, - maximum_desired_capacity / (double) K); + (double) capacity_after_gc / (double) K, + (double) minimum_desired_capacity / (double) K, + (double) maximum_desired_capacity / (double) K); gclog_or_tty->print_cr(" " - " free_after_gc : %6.1fK" - " used_after_gc : %6.1fK", - free_after_gc / (double) K, - used_after_gc / (double) K); + " free_after_gc: %6.1fK" + " used_after_gc: %6.1fK", + (double) free_after_gc / (double) K, + (double) used_after_gc / (double) K); gclog_or_tty->print_cr(" " " free_percentage: %6.2f", free_percentage); } - if (capacity() < minimum_desired_capacity) { + if (capacity_after_gc < minimum_desired_capacity) { // Don't expand unless it's significant size_t expand_bytes = minimum_desired_capacity - capacity_after_gc; expand(expand_bytes); if (PrintGC && Verbose) { - gclog_or_tty->print_cr(" expanding:" + gclog_or_tty->print_cr(" " + " expanding:" + " max_heap_size: %6.1fK" " minimum_desired_capacity: %6.1fK" " expand_bytes: %6.1fK", - minimum_desired_capacity / (double) K, - expand_bytes / (double) K); + (double) max_heap_size / (double) K, + (double) minimum_desired_capacity / (double) K, + (double) expand_bytes / (double) K); } // No expansion, now see if we want to shrink - } else if (capacity() > maximum_desired_capacity) { + } else if (capacity_after_gc > maximum_desired_capacity) { // Capacity too large, compute shrinking size size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity; shrink(shrink_bytes); if (PrintGC && Verbose) { gclog_or_tty->print_cr(" " " shrinking:" - " initSize: %.1fK" - " maximum_desired_capacity: %.1fK", - collector_policy()->initial_heap_byte_size() / (double) K, - maximum_desired_capacity / (double) K); - gclog_or_tty->print_cr(" " - " shrink_bytes: %.1fK", - shrink_bytes / (double) K); + " min_heap_size: %6.1fK" + " maximum_desired_capacity: %6.1fK" + " shrink_bytes: %6.1fK", + (double) min_heap_size / (double) K, + (double) maximum_desired_capacity / (double) K, + (double) shrink_bytes / (double) K); } } }