Using ThreadLocal Digester for NameBasedGenerator to avoid synchronized #88

magnoyu · 2023-10-20T14:44:10Z

Hi, does it make sense to create a non synchronized version of NameBasedGenerator if the user knows the digester is thread safe? With my M1, the synchronized is about 40% more in a 10 threads scenario.

Test 'Jug, name-based, ten threads' -> 358 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, concurrent, ten threads' -> 192 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, ten threads' -> 359 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, concurrent, ten threads' -> 193 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, ten threads' -> 354 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, concurrent, ten threads' -> 190 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, ten threads' -> 358 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, concurrent, ten threads' -> 197 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, ten threads' -> 367 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, concurrent, ten threads' -> 248 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, ten threads' -> 383 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, concurrent, ten threads' -> 200 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, ten threads' -> 370 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78
Test 'Jug, name-based, concurrent, ten threads' -> 194 msecs; last UUID: 5ec5b2a6-52cc-538f-8d16-59b7565f7f78

…d with ThreadLocal

cowtowncoder · 2023-10-20T22:20:41Z

General idea sounds reasonable, but I am not so sure about specific implementation. I suspect it'd be safer to use separate implementation with separate accessor for generator: keeping StringArgGenerator interface the same, but having separate implementation. And adding something like threadLocalNameBasedGenerator in Generators (or such). It might make sense to refactor common parts of 2 implementations (but not sure without looking more into this)
I think I'd like such implementation.

One future challenge is that ThreadLocal will be problematic with Project Loom where Threads will not be reused.

meiftikaralam · 2024-09-28T00:49:39Z

src/main/java/perf/MeasurePerformance.java

+    {
+        while (--rounds >= 0) {
+            final CyclicBarrier gate = new CyclicBarrier(11);
+            final MessageDigest digester = MessageDigest.getInstance("SHA-1");


nit: "SHA-1" can be declared as a constant

meiftikaralam · 2024-09-28T00:50:57Z

src/main/java/com/fasterxml/uuid/StringArgGenerator.java

+    /**
+     * Method for generating name-based UUIDs using specified name (serialized to
+     * bytes using UTF-8 encoding). No synchronization is performed on digester.
+     *  Digester is assumed to be created with ThreadLocal.


nit: It will be better if we can provide an use-case example when we should use this method.

meiftikaralam · 2024-09-28T00:51:28Z

src/main/java/com/fasterxml/uuid/StringArgGenerator.java

+    /**
+     * Method for generating name-based UUIDs using specified byte-serialization
+     * of name. No synchronization is performed on digester. Digester is assumed
+     * to be created with ThreadLocal.


same as above, can we put an example when to use this method

magno-cb and others added 2 commits October 20, 2023 10:23

Add concurrent generate to name based generator if digester is create…

972c28e

…d with ThreadLocal

Merge branch 'cowtowncoder:master' into master

b559585

meiftikaralam reviewed Sep 28, 2024

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Using ThreadLocal Digester for NameBasedGenerator to avoid synchronized #88

Using ThreadLocal Digester for NameBasedGenerator to avoid synchronized #88

magnoyu commented Oct 20, 2023

cowtowncoder commented Oct 20, 2023

meiftikaralam Sep 28, 2024

meiftikaralam Sep 28, 2024

meiftikaralam Sep 28, 2024

Using ThreadLocal Digester for NameBasedGenerator to avoid synchronized #88

Are you sure you want to change the base?

Using ThreadLocal Digester for NameBasedGenerator to avoid synchronized #88

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magnoyu commented Oct 20, 2023

cowtowncoder commented Oct 20, 2023

meiftikaralam Sep 28, 2024

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meiftikaralam Sep 28, 2024

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