Using fast_float library for faster parsing of 64 decimal strings. by filipecosta90 · Pull Request #11884 · redis/redis

filipecosta90 · 2023-03-06T23:44:23Z

We're using the fast_float library1 in our (compiled-in) floating-point fast_float_strtod implementation for faster and more portable parsing of 64 decimal strings.

The single file fast_float.h is an amalgamation of the entire library, which can be (re)generated with the amalgamate.py script (from the fast_float repository) via the command:

python3 ./script/amalgamate.py --license=MIT > $REDIS_SRC/deps/fast_float/fast_float.h

The used commit from fast_float library was the one from https://github.com/fastfloat/fast_float/releases/tag/v3.10.1

Still TODO:

finish the simplest possible makefile of fast_float ( but production ready )
validate the performance impact of this change via the benchmark SPEC
validate with @lemire that this is the best approach for including the fast_float lib
Fix the error raised in Added missing FASTFLOAT_ALLOWS_LEADING_PLUS ifdef check in parse_infnan fastfloat/fast_float#183 on fast_float original code and update fast_float.h
check gcc 12 baseline performance

lemire · 2023-03-07T02:04:47Z

Upgrading to 3.10.1 might be better: https://github.com/fastfloat/fast_float/releases/tag/v3.10.1

lemire · 2023-03-07T02:09:17Z

If you want to catch potential errors, you ought to add..

if(answer.ec != std::errc()) { /* do something */ }

(Note that the library follows the C++ standard so that's how we handle errors. We did not design this approach.)

@lemire I've added a error reporting via errno same like strtod.

lemire · 2023-03-07T02:45:11Z

This looks simple enough. My main concern is that you do not check for the error field after parsing. If you only rarely invoke strtod, then switching to the canonical fast_float API might be simpler. Whether this matters for your application, I do not know.

Note that fast_float relies on the C++17 standard API, so adopting the fast_float API is not akin to vendor lockin... it is a standard!!!

lemire · 2023-08-22T23:53:28Z

Note that the fast_float library has been adopted by webkit (Apple Safari) and other important systems such as GCC.

CLAassistant · 2024-03-24T23:09:20Z

All committers have signed the CLA.

lemire · 2024-08-18T22:56:24Z

The library is now part of Chromium (Chrome etc.).

fcostaoliveira · 2024-08-18T23:30:50Z

The library is now part of Chromium (Chrome etc.).

Thank you @lemire! I've updated to v6.1.4 using:

git clone https://github.com/fastfloat/fast_float
cd fast_float
git checkout v6.1.4
python3 ./script/amalgamate.py --license=MIT \
  > $REDIS_SRC/deps/fast_float/fast_float.h

will check the results on 2 tests in which we retrive 100 and 1000 elements with float scores and update this PR with results

fcostaoliveira · 2024-08-19T09:02:38Z

Automated performance analysis summary

This comment was automatically generated given there is performance data available.

Using platform named: intel64-ubuntu22.04-redis-icx1 to do the comparison.

In summary:

Detected a total of 1 stable tests between versions.
Detected a total of 2 improvements above the improvement water line.

You can check a comparison in detail via the grafana link

Comparison between unstable and fast_float.

Time Period from 5 months ago. (environment used: oss-standalone)

Improvements Table

Test Case	Baseline unstable (median obs. +- std.dev)	Comparison fast_float (median obs. +- std.dev)	% change (higher-better)	Note
memtier_benchmark-1Mkeys-load-zset-with-10-elements-double-score	92577 +- 0.8% (6 datapoints)	108545	17.2%	IMPROVEMENT
memtier_benchmark-1key-zset-100-elements-zrange-all-elements	19161 +- 0.7% (7 datapoints)	23062	20.4%	IMPROVEMENT

Improvements test regexp names: memtier_benchmark-1Mkeys-load-zset-with-10-elements-double-score|memtier_benchmark-1key-zset-100-elements-zrange-all-elements

Full Results table:

Test Case	Baseline unstable (median obs. +- std.dev)	Comparison fast_float (median obs. +- std.dev)	% change (higher-better)	Note
memtier_benchmark-1Mkeys-load-zset-with-10-elements-double-score	92577 +- 0.8% (6 datapoints)	108545	17.2%	IMPROVEMENT
memtier_benchmark-1key-zset-100-elements-zrange-all-elements	19161 +- 0.7% (7 datapoints)	23062	20.4%	IMPROVEMENT
memtier_benchmark-1key-zset-1K-elements-zrange-all-elements	3690 +- 0.2% (7 datapoints)	3659	-0.8%	No Change

sundb · 2024-08-19T09:43:37Z

https://github.com/sundb/redis/actions/runs/10450491468
some jobs build failed.

fcostaoliveira · 2024-08-19T10:09:11Z

https://github.com/sundb/redis/actions/runs/10450491468 some jobs build failed.

@sundb I believe they will all be related to g++ usage. Need to confirm with you guys that g++ dependency is something we're ok with. In the meantime will fix the failures :) thank you!

g++: No such file or directory

fcostaoliveira · 2024-08-20T00:24:06Z

https://github.com/sundb/redis/actions/runs/10450491468 some jobs build failed.

@sundb can you trigger it again. I believe it's all fixed now

sundb · 2024-08-20T01:42:52Z

@fcostaoliveira it failed on 32bit and freebsd: https://github.com/sundb/redis/actions/runs/10463748594

… default compilers on freebsd test

fcostaoliveira · 2024-08-22T00:16:13Z

@fcostaoliveira it failed on 32bit and freebsd: https://github.com/sundb/redis/actions/runs/10463748594

@sundb now fixed :)
https://github.com/filipecosta90/redis/actions/runs/10499383156/job/29086052819

…he CFLAGS via the main project

… GEOADD, GEORADIUS/GEOSEARCH, ZADD, and some ZUNION use-cases

…st (empty string passed) within getDoubleFromObject()

sundb · 2024-09-13T01:32:43Z

+            value = fast_float_strtod(o->ptr, &eptr);
+            /* check end pointer is not the null terminator, that the value a number,
+               and that the pointer to the last char is not equal to the first (empty string passed) */
+            if (eptr[0] != '\0' || isnan(value) || (eptr[0] == ((char *)o->ptr)[0])) return C_ERR;


why not keep the old string2d() which also uses fast_float_strtod()?

indeed. Addressed in de8b1be

fcostaoliveira · 2024-09-14T19:46:28Z

@sundb after rebasing from unstable and also doing the latest PR requests confirmed all improvements stay the same, with improvements reaching 26% on the achievable ops/sec (without pipelining) :

To replicate:

redis-benchmarks-spec-client-runner --tests-regexp "memtier_benchmark-1Mkeys-load-zset-with-10-elements-double-score|memtier_benchmark-1key-zset-100-elements-zrange-all-elements" --flushall_on_every_test_start --flushall_on_every_test_end  --cpuset_start_pos 2 --override-memtier-test-time 60

Results:

Test Name	Metric	unstable `9146ac0`	this PR `de8b1be`	% Change
memtier_benchmark-1key-zset-100-elements-zrange-all-elements	Ops/sec	16710.92	21076.97	26.13%
memtier_benchmark-1key-zset-100-elements-zrange-all-elements	p50 including RTT	9.343	7.583	18.84%
memtier_benchmark-1Mkeys-load-zset-with-10-elements-double-score	Ops/sec	68801.57	86289.12	25.42%
memtier_benchmark-1Mkeys-load-zset-with-10-elements-double-score	p50 including RTT	2.495	2.063	17.31%

fcostaoliveira · 2024-10-19T05:16:20Z

CE Performance Automation : step 2 of 2 (benchmark) FINISHED.

This comment was automatically generated given a benchmark was triggered.

Started benchmark suite at 2024-10-20 07:59:24.154571 and took 1.256626 seconds to finish.
Status: [################################################################################] 100.0% completed.

In total will run 1 benchmarks.
- 0 pending.
- 1 completed:
- 0 successful.
- 1 failed.
You can check a the status in detail via the grafana link

#13845) Since #11884, what was previously accepted as a valid input (hexadecimal string) before 8.0 returned an error. This PR addresses it. To avoid performance penalties if hints the compiler that the fallbacks are not likely to happen. Furthermore, we were ignoring std::result_out_of_range outputs from fast_float. This PR addresses it as well and includes tests for both identified scenarios. --------- Co-authored-by: debing.sun <debing.sun@redis.com>

filipecosta90 added the action:run-benchmark Triggers the benchmark suite for this Pull Request label Mar 6, 2023

filipecosta90 mentioned this pull request Mar 6, 2023

[NEW] Performance: Improve string to floating-point conversion time using Eisel-Lemire algorithm on 99% of the cases, while ensuring correctness of 100% of cases #8825

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lemire reviewed Mar 7, 2023

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filipecosta90 added action:run-benchmark Triggers the benchmark suite for this Pull Request and removed action:run-benchmark Triggers the benchmark suite for this Pull Request labels Mar 13, 2023

vlsi mentioned this pull request May 9, 2023

Please bundle LICENSE/NOTICE files in the produced jar files wrandelshofer/FastDoubleParser#38

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fcostaoliveira added action:run-benchmark Triggers the benchmark suite for this Pull Request and removed action:run-benchmark Triggers the benchmark suite for this Pull Request labels Aug 18, 2024

Using fast_float library for faster parsing of 64 decimal strings.

ea4a9a8

filipecosta90 force-pushed the fast_float branch from fcd5155 to ea4a9a8 Compare August 19, 2024 13:27

fcostaoliveira requested a review from sundb August 20, 2024 00:34

fcostaoliveira added 4 commits August 20, 2024 13:23

Added multilib gcc/g++ to 32bit ci. setting clang and clang++ has the…

1fe5efb

… default compilers on freebsd test

Enabled 32bit library build for fast_float

18b0337

Enabled -DFASTFLOAT_ALLOWS_LEADING_PLUS. Check fastfloat/fast_float#183

00a35e0

Added gcc dependency to freebsd setup stage on CI. To be able to use g++

a4ca82d

fcostaoliveira requested a review from lemire August 22, 2024 00:16

fcostaoliveira added the action:run-benchmark Triggers the benchmark suite for this Pull Request label Aug 22, 2024

fcostaoliveira added 4 commits August 26, 2024 12:48

Avoid loosing the fastfloat specific compile flags when we override t…

1e84f28

…he CFLAGS via the main project

Using fast_float on getDoubleFromObject(): impacts RM_StringToDouble,…

dfec28d

… GEOADD, GEORADIUS/GEOSEARCH, ZADD, and some ZUNION use-cases

Added check that the pointer to the last char is not equal to the fir…

1c2dfb3

…st (empty string passed) within getDoubleFromObject()

Merge remote-tracking branch 'origin/unstable' into fast_float

31aaf4c

fcostaoliveira removed the action:run-benchmark Triggers the benchmark suite for this Pull Request label Sep 12, 2024

sundb reviewed Sep 13, 2024

View reviewed changes

fcostaoliveira added 2 commits September 14, 2024 19:55

Merge remote-tracking branch 'origin/unstable' into fast_float

b598b9b

Fixes per PR review

de8b1be

fcostaoliveira requested a review from sundb September 14, 2024 19:09

sundb approved these changes Sep 15, 2024

View reviewed changes

sundb merged commit af7fca7 into redis:unstable Sep 15, 2024

meiravgri mentioned this pull request Oct 6, 2024

[MOD-7897, MOD-7936] link dynamically to stdc++, fix ACL test RediSearch/RediSearch#5073

Merged

oshadmi mentioned this pull request Dec 16, 2024

MOD-8578: Use fast_float library RediSearch/RediSearch#5349

Merged

2 tasks

fcostaoliveira mentioned this pull request Mar 6, 2025

Fix string2d usage in case of hexadecimal strings parsing and overflow #13845

Merged

3 tasks

mhassan1 mentioned this pull request May 8, 2025

Redis stable version updated, breaks redis-memory-server install mhassan1/redis-memory-server#48

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sundb added this to Redis 8.0 Aug 15, 2025

github-project-automation Bot moved this to Todo in Redis 8.0 Aug 15, 2025

sundb moved this from Todo to Done in Redis 8.0 Aug 15, 2025

fcostaoliveira mentioned this pull request Jan 12, 2026

Replace fast_float C++ library with pure C implementation #14661

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Automated performance analysis summary

Comparison between unstable and fast_float.

Improvements Table

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CE Performance Automation : step 2 of 2 (benchmark) FINISHED.

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