Apply snappy compression to Configuration Cache entries #29643

bamboo · 2024-06-21T14:39:05Z

Apply snappy compression to Configuration Cache entries

Compression and encryption are offloaded to a separate thread, utilizing a pool of byte buffers capped at a maximum memory working set of 16MB.

The resulting files are 1/5th of their original size. Storing might be marginally slower in some cases, but loading is as fast or faster in all tested scenarios.

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bamboo · 2024-06-21T14:39:21Z

@bot-gradle test APT

bot-gradle · 2024-06-21T14:39:28Z

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abstratt · 2024-06-21T17:42:43Z

...n/configuration-cache/src/main/kotlin/org/gradle/internal/cc/impl/io/ParallelOutputStream.kt

+         * Determines the maximum memory working set: [bufferCount] * [bufferCapacity].
+         * The default maximum working set is `32MB`.
+         */
+        val bufferCount = System.getProperty("org.gradle.configuration-cache.internal.buffer-count", null)?.toInt()


Is this right? 1 million buffers that are 32 bit long each? Normally, I'd expect the other way around.

Is this right? 1 million buffers that are 32 bit long each? Normally, I'd expect the other way around.

Yes, perhaps the term buffer is not the best choice here. A better analogy might be of a packet (like in UDP). These are used to quickly send the encoded information from the producer to the writer thread for compression >> encryption >> disk IO.

@abstratt Please take another look, I changed the code to the packet analogy.

32 bit long

bytes

mlopatkin

I now see that the graph walking in smaller builds is probably stuck on waiting for the writer thread to finish compression. We still may win something back by tweaking compression ratio, but I don't have better ideas.

...n/configuration-cache/src/main/kotlin/org/gradle/internal/cc/impl/io/ParallelOutputStream.kt

mlopatkin · 2024-06-21T21:04:30Z

...n/configuration-cache/src/main/kotlin/org/gradle/internal/cc/impl/io/ParallelOutputStream.kt

+            } finally {
+                // in case of failure, this releases some memory until the
+                // producer realizes there was a failure
+                ready.clear()


...n/configuration-cache/src/main/kotlin/org/gradle/internal/cc/impl/io/ParallelOutputStream.kt

...tion/configuration-cache/src/main/kotlin/org/gradle/internal/cc/impl/ConfigurationCacheIO.kt

bamboo · 2024-06-24T14:15:39Z

...egTest/groovy/org/gradle/internal/cc/impl/ConfigurationCacheEncryptionIntegrationTest.groovy

    }

    def "configuration cache encryption enablement is #enabled if kind=#kind"() {
+        Assume.assumeTrue("Compression no longer exposes the raw data", enabled)


🤔 I'm not sure what to do with this test. @abstratt, do you think we still need it?

One thing we are losing here is the ability of detecting a regression where a bug introduced to CC effectively disabled encryption.

We would need to make compression optional (even if behind an internal option), so we could disable it for this test case. May be a good thing to have (for debugging compression performance in the field), and seems more or less trivial to implement, but I will not push for it.

bamboo · 2024-06-24T15:56:42Z

@bot-gradle test ACC

bot-gradle · 2024-06-24T15:56:46Z

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mlopatkin

LGTM with nits

mlopatkin · 2024-06-24T19:39:16Z

...n/configuration-cache/src/main/kotlin/org/gradle/internal/cc/impl/io/ParallelOutputStream.kt

+
+    private
+    fun flip(packet: Buffer) {
+        // packet.flip() is not available in Java 8


💅 I've just remembered the whole story here: Buffer flip() is in Java since NIO's inception, and therefore available for ByteBuffer as well. A covariant override ByteBuffer flip() is a new addition of Java 9, and it is what trips the compiler over. I guess, with the typing you have here packet.flip() should already work.

Yeah, I can see that now.

mlopatkin · 2024-06-24T19:48:31Z

...n/configuration-cache/src/main/kotlin/org/gradle/internal/cc/impl/io/ParallelOutputStream.kt

+
+
+private
+typealias Packet = java.nio.ByteBuffer


🤔 TBH, I find the code with this alias less readable. As a Java developer I know what a ByteBuffer can do, but now have to jump an extra hop to connect the Packet name to it. I don't insist on changing this.

💅 I wonder if chunk is a better name for the pieces we're tossing around here, because a packet somewhat implies having metadata.

chunk seems like a better name indeed, thanks. I also agree about the alias.

…te thread

- Make it easier to run a specific set of benchmarks

Based on benchmark results.

github-actions · 2024-08-15T15:10:19Z

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed in 14 days if no further activity occurs. If you don't want the stale bot to close it, then set a milestone for it.

bamboo added a:feature A new functionality in:configuration-cache Configuration Caching a:performance-improvement Performance improvement potential labels Jun 21, 2024

bamboo added this to the 8.10 RC1 milestone Jun 21, 2024

bamboo self-assigned this Jun 21, 2024

abstratt reviewed Jun 21, 2024

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mlopatkin reviewed Jun 21, 2024

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bamboo force-pushed the bamboo/cc/compress-in-parallel branch from 3827678 to 9ac5192 Compare June 23, 2024 15:26

bamboo commented Jun 24, 2024

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bamboo marked this pull request as ready for review June 24, 2024 14:33

bamboo requested a review from a team as a code owner June 24, 2024 14:33

bamboo requested review from abstratt and alllex and removed request for a team June 24, 2024 14:33

bamboo force-pushed the bamboo/cc/compress-in-parallel branch 2 times, most recently from 61e4c1a to cb8df0c Compare June 24, 2024 19:06

mlopatkin approved these changes Jun 24, 2024

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bamboo force-pushed the bamboo/cc/compress-in-parallel branch 2 times, most recently from 6991ec1 to d4385f1 Compare June 27, 2024 17:41

bamboo added 4 commits June 28, 2024 12:00

Apply snappy compression to Configuration Cache entries

7e5520e

Compress and encrypt configuration cache work graph entry in a separa…

1c33b17

…te thread

Disable encryption test temporarily

fe60802

Add jmh benchmark comparing multiple cc store strategies

8305de5

bamboo force-pushed the bamboo/cc/compress-in-parallel branch from d4385f1 to 8305de5 Compare June 28, 2024 15:00

bamboo added 2 commits June 28, 2024 13:51

Polish CCStoreBenchmark

abb8d40

- Make it easier to run a specific set of benchmarks

Let ParallelOutputStream use an ArrayBlockingQueue

e7f31ba

Based on benchmark results.

bamboo removed this from the 8.10 RC1 milestone Jul 16, 2024

Apply snappy compression to Configuration Cache entries #29643

Apply snappy compression to Configuration Cache entries #29643

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