Re: RFR: 8333396: Performance regression of DecimalFormat.format [v17]
On Mon, 8 Jul 2024 02:32:17 GMT, lingjun-cg wrote:
>> ### Performance regression of DecimalFormat.format
>> From the output of perf, we can see the hottest regions contain atomic
>> instructions. But when run with JDK 11, there is no such problem. The
>> reason is the removed biased locking.
>> The DecimalFormat uses StringBuffer everywhere, and StringBuffer itself
>> contains many synchronized methods.
>> So I added support for some new methods that accept StringBuilder which is
>> lock-free.
>>
>> ### Benchmark testcase
>>
>> @BenchmarkMode(Mode.AverageTime)
>> @Warmup(iterations = 5, time = 500, timeUnit = TimeUnit.MILLISECONDS)
>> @Measurement(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
>> @State(Scope.Thread)
>> @OutputTimeUnit(TimeUnit.NANOSECONDS)
>> public class JmhDecimalFormat {
>>
>> private DecimalFormat format;
>>
>> @Setup(Level.Trial)
>> public void setup() {
>> format = new DecimalFormat("#0.0");
>> }
>>
>> @Benchmark
>> public void testNewAndFormat() throws InterruptedException {
>> new DecimalFormat("#0.0").format(9524234.1236457);
>> }
>>
>> @Benchmark
>> public void testNewOnly() throws InterruptedException {
>> new DecimalFormat("#0.0");
>> }
>>
>> @Benchmark
>> public void testFormatOnly() throws InterruptedException {
>> format.format(9524234.1236457);
>> }
>> }
>>
>>
>> ### Test result
>> Current JDK before optimize
>>
>> Benchmark Mode CntScore Error Units
>> JmhDecimalFormat.testFormatOnly avgt 50 642.099 ? 1.253 ns/op
>> JmhDecimalFormat.testNewAndFormat avgt 50 989.307 ? 3.676 ns/op
>> JmhDecimalFormat.testNewOnly avgt 50 303.381 ? 5.252 ns/op
>>
>>
>>
>> Current JDK after optimize
>>
>> Benchmark Mode CntScore Error Units
>> JmhDecimalFormat.testFormatOnlyavgt 50 351.499 ? 0.761 ns/op
>> JmhDecimalFormat.testNewAndFormat avgt 50 615.145 ? 2.478 ns/op
>> JmhDecimalFormat.testNewOnly avgt 50 209.874 ? 9.951 ns/op
>>
>>
>> ### JDK 11
>>
>> Benchmark Mode CntScore Error Units
>> JmhDecimalFormat.testFormatOnlyavgt 50 364.214 ? 1.191 ns/op
>> JmhDecimalFormat.testNewAndFormat avgt 50 658.699 ? 2.311 ns/op
>> JmhDecimalFormat.testNewOnly avgt 50 248.300 ? 5.158 ns/op
>
> lingjun-cg has updated the pull request incrementally with one additional
> commit since the last revision:
>
> 896: Performance regression of DecimalFormat.format
I believe the `static MessageFormat.format(...` also has similar incorrect
"this is equivalent ..." wording, if you could please include that as well. I
think we should also rename the issue (and CSR) as well since the scope has
changed. Something along the lines of "Use StringBuilder internally for
java.text.Format.* formatting".
-
Changes requested by jlu (Committer).
PR Review: https://git.openjdk.org/jdk/pull/19513#pullrequestreview-2163963773
Re: RFR: 8333396: Performance regression of DecimalFormat.format [v17]
On Mon, 8 Jul 2024 03:06:17 GMT, Chen Liang wrote: > Quick question about the violation of the "This is equivalent to" spec: Does > our new implementation lead to any observable side effects that make the > returned results or thrown exceptions different from that of `format(obj, new > StringBuffer(), new FieldPosition(0)).toString()`? > > In the ClassFile API, there are similar "behave as if" notes such as > > https://github.com/openjdk/jdk/blob/3f37c5718d676b7001e6a084aed3ba645745a144/src/java.base/share/classes/java/lang/classfile/ClassFile.java#L433-L438 > > , yet we don't restrict implementations as the API surface, including the > return an exception result and side effects are the same. AFAIK, there will be no behavioral difference, but I think CSR has to be accompanied with this issue to remove that wording, because it is not correct anymore. - PR Comment: https://git.openjdk.org/jdk/pull/19513#issuecomment-2214627225
Re: RFR: 8333396: Performance regression of DecimalFormat.format [v17]
On Mon, 8 Jul 2024 02:32:17 GMT, lingjun-cg wrote:
>> ### Performance regression of DecimalFormat.format
>> From the output of perf, we can see the hottest regions contain atomic
>> instructions. But when run with JDK 11, there is no such problem. The
>> reason is the removed biased locking.
>> The DecimalFormat uses StringBuffer everywhere, and StringBuffer itself
>> contains many synchronized methods.
>> So I added support for some new methods that accept StringBuilder which is
>> lock-free.
>>
>> ### Benchmark testcase
>>
>> @BenchmarkMode(Mode.AverageTime)
>> @Warmup(iterations = 5, time = 500, timeUnit = TimeUnit.MILLISECONDS)
>> @Measurement(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
>> @State(Scope.Thread)
>> @OutputTimeUnit(TimeUnit.NANOSECONDS)
>> public class JmhDecimalFormat {
>>
>> private DecimalFormat format;
>>
>> @Setup(Level.Trial)
>> public void setup() {
>> format = new DecimalFormat("#0.0");
>> }
>>
>> @Benchmark
>> public void testNewAndFormat() throws InterruptedException {
>> new DecimalFormat("#0.0").format(9524234.1236457);
>> }
>>
>> @Benchmark
>> public void testNewOnly() throws InterruptedException {
>> new DecimalFormat("#0.0");
>> }
>>
>> @Benchmark
>> public void testFormatOnly() throws InterruptedException {
>> format.format(9524234.1236457);
>> }
>> }
>>
>>
>> ### Test result
>> Current JDK before optimize
>>
>> Benchmark Mode CntScore Error Units
>> JmhDecimalFormat.testFormatOnly avgt 50 642.099 ? 1.253 ns/op
>> JmhDecimalFormat.testNewAndFormat avgt 50 989.307 ? 3.676 ns/op
>> JmhDecimalFormat.testNewOnly avgt 50 303.381 ? 5.252 ns/op
>>
>>
>>
>> Current JDK after optimize
>>
>> Benchmark Mode CntScore Error Units
>> JmhDecimalFormat.testFormatOnlyavgt 50 351.499 ? 0.761 ns/op
>> JmhDecimalFormat.testNewAndFormat avgt 50 615.145 ? 2.478 ns/op
>> JmhDecimalFormat.testNewOnly avgt 50 209.874 ? 9.951 ns/op
>>
>>
>> ### JDK 11
>>
>> Benchmark Mode CntScore Error Units
>> JmhDecimalFormat.testFormatOnlyavgt 50 364.214 ? 1.191 ns/op
>> JmhDecimalFormat.testNewAndFormat avgt 50 658.699 ? 2.311 ns/op
>> JmhDecimalFormat.testNewOnly avgt 50 248.300 ? 5.158 ns/op
>
> lingjun-cg has updated the pull request incrementally with one additional
> commit since the last revision:
>
> 896: Performance regression of DecimalFormat.format
Quick question about the violation of the "This is equivalent to" spec: Does
our new implementation lead to any observable side effects that make the
returned results or thrown exceptions different from that of `format(obj, new
StringBuffer(), new FieldPosition(0)).toString()`?
In the ClassFile API, there are similar "behave as if" notes such as
https://github.com/openjdk/jdk/blob/3f37c5718d676b7001e6a084aed3ba645745a144/src/java.base/share/classes/java/lang/classfile/ClassFile.java#L433-L438,
yet we don't restrict implementations as the API surface, including the return
an exception result and side effects are the same.
-
PR Comment: https://git.openjdk.org/jdk/pull/19513#issuecomment-2212893099
Re: RFR: 8333396: Performance regression of DecimalFormat.format [v17]
> ### Performance regression of DecimalFormat.format
> From the output of perf, we can see the hottest regions contain atomic
> instructions. But when run with JDK 11, there is no such problem. The reason
> is the removed biased locking.
> The DecimalFormat uses StringBuffer everywhere, and StringBuffer itself
> contains many synchronized methods.
> So I added support for some new methods that accept StringBuilder which is
> lock-free.
>
> ### Benchmark testcase
>
> @BenchmarkMode(Mode.AverageTime)
> @Warmup(iterations = 5, time = 500, timeUnit = TimeUnit.MILLISECONDS)
> @Measurement(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
> @State(Scope.Thread)
> @OutputTimeUnit(TimeUnit.NANOSECONDS)
> public class JmhDecimalFormat {
>
> private DecimalFormat format;
>
> @Setup(Level.Trial)
> public void setup() {
> format = new DecimalFormat("#0.0");
> }
>
> @Benchmark
> public void testNewAndFormat() throws InterruptedException {
> new DecimalFormat("#0.0").format(9524234.1236457);
> }
>
> @Benchmark
> public void testNewOnly() throws InterruptedException {
> new DecimalFormat("#0.0");
> }
>
> @Benchmark
> public void testFormatOnly() throws InterruptedException {
> format.format(9524234.1236457);
> }
> }
>
>
> ### Test result
> Current JDK before optimize
>
> Benchmark Mode CntScore Error Units
> JmhDecimalFormat.testFormatOnly avgt 50 642.099 ? 1.253 ns/op
> JmhDecimalFormat.testNewAndFormat avgt 50 989.307 ? 3.676 ns/op
> JmhDecimalFormat.testNewOnly avgt 50 303.381 ? 5.252 ns/op
>
>
>
> Current JDK after optimize
>
> Benchmark Mode CntScore Error Units
> JmhDecimalFormat.testFormatOnlyavgt 50 351.499 ? 0.761 ns/op
> JmhDecimalFormat.testNewAndFormat avgt 50 615.145 ? 2.478 ns/op
> JmhDecimalFormat.testNewOnly avgt 50 209.874 ? 9.951 ns/op
>
>
> ### JDK 11
>
> Benchmark Mode CntScore Error Units
> JmhDecimalFormat.testFormatOnlyavgt 50 364.214 ? 1.191 ns/op
> JmhDecimalFormat.testNewAndFormat avgt 50 658.699 ? 2.311 ns/op
> JmhDecimalFormat.testNewOnly avgt 50 248.300 ? 5.158 ns/op
lingjun-cg has updated the pull request incrementally with one additional
commit since the last revision:
896: Performance regression of DecimalFormat.format
-
Changes:
- all: https://git.openjdk.org/jdk/pull/19513/files
- new: https://git.openjdk.org/jdk/pull/19513/files/7122c2c8..d675bcbf
Webrevs:
- full: https://webrevs.openjdk.org/?repo=jdk&pr=19513&range=16
- incr: https://webrevs.openjdk.org/?repo=jdk&pr=19513&range=15-16
Stats: 5 lines in 1 file changed: 0 ins; 4 del; 1 mod
Patch: https://git.openjdk.org/jdk/pull/19513.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/19513/head:pull/19513
PR: https://git.openjdk.org/jdk/pull/19513
