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8144527: NewSizeThreadIncrease would make an overflow

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Revert to previous value if NewSizeThreadIncrease related calculation overflows

Reviewed-by: jwilhelm, mgerdin, mchernov
This commit is contained in:
Sangheon Kim 2016-01-05 17:05:13 -08:00
parent 73c45490a2
commit 7479dffbc6
3 changed files with 168 additions and 6 deletions
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43
hotspot/src/share/vm/gc/serial/defNewGeneration.cpp
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@ -364,6 +364,36 @@ bool DefNewGeneration::expand(size_t bytes) {
return success;
}
size_t DefNewGeneration::adjust_for_thread_increase(size_t new_size_candidate,
size_t new_size_before,
size_t alignment) const {
size_t desired_new_size = new_size_before;
if (NewSizeThreadIncrease > 0) {
int threads_count;
size_t thread_increase_size = 0;
// 1. Check an overflow at 'threads_count * NewSizeThreadIncrease'.
threads_count = Threads::number_of_non_daemon_threads();
if (NewSizeThreadIncrease <= max_uintx / threads_count) {
thread_increase_size = threads_count * NewSizeThreadIncrease;
// 2. Check an overflow at 'new_size_candidate + thread_increase_size'.
if (new_size_candidate <= max_uintx - thread_increase_size) {
new_size_candidate += thread_increase_size;
// 3. Check an overflow at 'align_size_up'.
size_t aligned_max = ((max_uintx - alignment) & ~(alignment-1));
if (new_size_candidate <= aligned_max) {
desired_new_size = align_size_up(new_size_candidate, alignment);
}
}
}
}
return desired_new_size;
}
void DefNewGeneration::compute_new_size() {
// This is called after a GC that includes the old generation, so from-space
// will normally be empty.
@ -385,12 +415,13 @@ void DefNewGeneration::compute_new_size() {
// All space sizes must be multiples of Generation::GenGrain.
size_t alignment = Generation::GenGrain;
// Compute desired new generation size based on NewRatio and
// NewSizeThreadIncrease
size_t desired_new_size = old_size/NewRatio;
int threads_count = Threads::number_of_non_daemon_threads();
size_t thread_increase_size = threads_count * NewSizeThreadIncrease;
desired_new_size = align_size_up(desired_new_size + thread_increase_size, alignment);
int threads_count = 0;
size_t thread_increase_size = 0;
size_t new_size_candidate = old_size / NewRatio;
// Compute desired new generation size based on NewRatio and NewSizeThreadIncrease
// and reverts to previous value if any overflow happens
size_t desired_new_size = adjust_for_thread_increase(new_size_candidate, new_size_before, alignment);
// Adjust new generation size
desired_new_size = MAX2(MIN2(desired_new_size, max_new_size), min_new_size);