Replace StringBuilder#append(String) with StringBuilder#append(char) by smola · Pull Request #8008 · DataDog/dd-trace-java

smola · 2024-11-25T07:55:12Z

What Does This Do

Replace StringBuilder#append(String) with StringBuilder#append(char) when a single character is used.

Motivation

Detected with java-best-practices/sb-append-char static analysis rule.

Additional Notes

Contributor Checklist

Format the title according the contribution guidelines
Assign the type: and (comp: or inst:) labels in addition to any usefull labels
Squash your commits prior merging or merge using GitHub's Squash and merge
Don't use close, fix or any linking keywords when referencing an issue.
Use solves instead, and assign the PR milestone to the issue
Update the public documentation in case of new configuration flag or behavior

Jira ticket: [PROJ-IDENT]

pr-commenter · 2024-11-25T08:15:14Z

Debugger benchmarks

Parameters

	Baseline	Candidate
baseline_or_candidate	baseline	candidate
ci_job_date	1732528930	1732529321
end_time	2024-11-25T10:03:26	2024-11-25T10:09:58
git_branch	master	smola/single-char
git_commit_sha	`b36006c`	`0fcd18e`
start_time	2024-11-25T10:02:11	2024-11-25T10:08:42

See matching parameters

	Baseline	Candidate
ci_job_id	718499533	718499533
ci_pipeline_id	49833603	49833603
cpu_model	Intel(R) Xeon(R) Platinum 8259CL CPU @ 2.50GHz	Intel(R) Xeon(R) Platinum 8259CL CPU @ 2.50GHz
git_commit_date	1732527941	1732527941

Summary

Found 5 performance improvements and 0 performance regressions! Performance is the same for 3 metrics, 7 unstable metrics.

scenario	Δ mean agg_http_req_duration_min	Δ mean agg_http_req_duration_p50	Δ mean agg_http_req_duration_p75	Δ mean agg_http_req_duration_p99	Δ mean throughput
scenario:loop	better [-723.086µs; -684.346µs] or [-6.638%; -6.282%]	better [-754.246µs; -685.296µs] or [-6.812%; -6.190%]	better [-750.200µs; -631.285µs] or [-6.734%; -5.667%]	better [-934.660µs; -508.794µs] or [-8.098%; -4.408%]	better [+4.723op/s; +7.182op/s] or [+5.290%; +8.044%]

See unchanged results

scenario	Δ mean agg_http_req_duration_min	Δ mean agg_http_req_duration_p50	Δ mean agg_http_req_duration_p75	Δ mean agg_http_req_duration_p99	Δ mean throughput
scenario:noprobe	unstable [-61.067µs; +30.030µs] or [-21.687%; +10.665%]	unstable [-80.728µs; +39.283µs] or [-24.754%; +12.045%]	unstable [-89.696µs; +48.576µs] or [-26.246%; +14.214%]	unstable [-1035.227µs; +372.891µs] or [-109.493%; +39.440%]	same
scenario:basic	same	same	unstable [-17.052µs; +22.418µs] or [-5.246%; +6.897%]	unstable [-277.770µs; +94.856µs] or [-44.603%; +15.232%]	unstable [-155.976op/s; +155.976op/s] or [-6.239%; +6.239%]

Request duration reports for reports

gantt
    title reports - request duration [CI 0.99] : candidate=None, baseline=None
    dateFormat X
    axisFormat %s
section baseline
noprobe (326.122 µs) : 249, 403
.   : milestone, 326,
basic (311.992 µs) : 296, 328
.   : milestone, 312,
loop (11.072 ms) : 11034, 11110
.   : milestone, 11072,
section candidate
noprobe (305.4 µs) : 282, 329
.   : milestone, 305,
basic (317.267 µs) : 309, 325
.   : milestone, 317,
loop (10.352 ms) : 10327, 10377
.   : milestone, 10352,

baseline results

Scenario	Request median duration [CI 0.99]
noprobe	326.122 µs [248.761 µs, 403.483 µs]
basic	311.992 µs [296.415 µs, 327.569 µs]
loop	11.072 ms [11.034 ms, 11.11 ms]

candidate results

Scenario	Request median duration [CI 0.99]
noprobe	305.4 µs [281.685 µs, 329.114 µs]
basic	317.267 µs [309.31 µs, 325.224 µs]
loop	10.352 ms [10.327 ms, 10.377 ms]

pr-commenter · 2024-11-25T08:34:39Z

Benchmarks

Startup

Load

Dacapo

Parameters

	Baseline	Candidate
baseline_or_candidate	baseline	candidate
git_branch	master	smola/single-char
git_commit_date	1732532650	1732535609
git_commit_sha	`f2d21ae`	`7d452a8`
release_version	1.43.0-SNAPSHOT~f2d21ae588	1.44.0-SNAPSHOT~7d452a8e9a

See matching parameters

	Baseline	Candidate
application	biojava	biojava
ci_job_date	1732537497	1732537497
ci_job_id	718676643	718676643
ci_pipeline_id	49844883	49844883
cpu_model	Intel(R) Xeon(R) Platinum 8259CL CPU @ 2.50GHz	Intel(R) Xeon(R) Platinum 8259CL CPU @ 2.50GHz
variant	appsec	appsec

Summary

Found 0 performance improvements and 0 performance regressions! Performance is the same for 12 metrics, 0 unstable metrics.

Execution time for biojava

gantt
    title biojava - execution time [CI 0.99] : candidate=1.44.0-SNAPSHOT~7d452a8e9a, baseline=1.43.0-SNAPSHOT~f2d21ae588
    dateFormat X
    axisFormat %s
section baseline
no_agent (14.942 s) : 14942000, 14942000
.   : milestone, 14942000,
appsec (15.077 s) : 15077000, 15077000
.   : milestone, 15077000,
iast (18.604 s) : 18604000, 18604000
.   : milestone, 18604000,
iast_GLOBAL (17.737 s) : 17737000, 17737000
.   : milestone, 17737000,
profiling (15.099 s) : 15099000, 15099000
.   : milestone, 15099000,
tracing (15.131 s) : 15131000, 15131000
.   : milestone, 15131000,
section candidate
no_agent (14.928 s) : 14928000, 14928000
.   : milestone, 14928000,
appsec (15.063 s) : 15063000, 15063000
.   : milestone, 15063000,
iast (18.723 s) : 18723000, 18723000
.   : milestone, 18723000,
iast_GLOBAL (18.252 s) : 18252000, 18252000
.   : milestone, 18252000,
profiling (14.935 s) : 14935000, 14935000
.   : milestone, 14935000,
tracing (14.844 s) : 14844000, 14844000
.   : milestone, 14844000,

baseline results

Variant	Execution Time [CI 0.99]	Δ no_agent
no_agent	14.942 s [14.942 s, 14.942 s]	-
appsec	15.077 s [15.077 s, 15.077 s]	135.0 ms (0.9%)
iast	18.604 s [18.604 s, 18.604 s]	3.662 s (24.5%)
iast_GLOBAL	17.737 s [17.737 s, 17.737 s]	2.795 s (18.7%)
profiling	15.099 s [15.099 s, 15.099 s]	157.0 ms (1.1%)
tracing	15.131 s [15.131 s, 15.131 s]	189.0 ms (1.3%)

candidate results

Variant	Execution Time [CI 0.99]	Δ no_agent
no_agent	14.928 s [14.928 s, 14.928 s]	-
appsec	15.063 s [15.063 s, 15.063 s]	135.0 ms (0.9%)
iast	18.723 s [18.723 s, 18.723 s]	3.795 s (25.4%)
iast_GLOBAL	18.252 s [18.252 s, 18.252 s]	3.324 s (22.3%)
profiling	14.935 s [14.935 s, 14.935 s]	7.0 ms (0.0%)
tracing	14.844 s [14.844 s, 14.844 s]	-84.0 ms (-0.6%)

Execution time for tomcat

gantt
    title tomcat - execution time [CI 0.99] : candidate=1.44.0-SNAPSHOT~7d452a8e9a, baseline=1.43.0-SNAPSHOT~f2d21ae588
    dateFormat X
    axisFormat %s
section baseline
no_agent (1.469 ms) : 1457, 1480
.   : milestone, 1469,
appsec (2.341 ms) : 2299, 2383
.   : milestone, 2341,
iast (2.092 ms) : 2039, 2145
.   : milestone, 2092,
iast_GLOBAL (2.136 ms) : 2083, 2189
.   : milestone, 2136,
profiling (1.956 ms) : 1914, 1999
.   : milestone, 1956,
tracing (1.927 ms) : 1887, 1968
.   : milestone, 1927,
section candidate
no_agent (1.473 ms) : 1462, 1485
.   : milestone, 1473,
appsec (2.35 ms) : 2308, 2392
.   : milestone, 2350,
iast (2.088 ms) : 2035, 2141
.   : milestone, 2088,
iast_GLOBAL (2.133 ms) : 2079, 2186
.   : milestone, 2133,
profiling (1.941 ms) : 1899, 1983
.   : milestone, 1941,
tracing (1.929 ms) : 1889, 1970
.   : milestone, 1929,

baseline results

Variant	Execution Time [CI 0.99]	Δ no_agent
no_agent	1.469 ms [1.457 ms, 1.48 ms]	-
appsec	2.341 ms [2.299 ms, 2.383 ms]	872.174 µs (59.4%)
iast	2.092 ms [2.039 ms, 2.145 ms]	623.223 µs (42.4%)
iast_GLOBAL	2.136 ms [2.083 ms, 2.189 ms]	666.96 µs (45.4%)
profiling	1.956 ms [1.914 ms, 1.999 ms]	487.606 µs (33.2%)
tracing	1.927 ms [1.887 ms, 1.968 ms]	458.633 µs (31.2%)

candidate results

Variant	Execution Time [CI 0.99]	Δ no_agent
no_agent	1.473 ms [1.462 ms, 1.485 ms]	-
appsec	2.35 ms [2.308 ms, 2.392 ms]	876.601 µs (59.5%)
iast	2.088 ms [2.035 ms, 2.141 ms]	614.556 µs (41.7%)
iast_GLOBAL	2.133 ms [2.079 ms, 2.186 ms]	659.499 µs (44.8%)
profiling	1.941 ms [1.899 ms, 1.983 ms]	467.505 µs (31.7%)
tracing	1.929 ms [1.889 ms, 1.97 ms]	455.973 µs (30.9%)

PerfectSlayer

I hope you used a tool to make all the changes 😅

smola · 2024-11-25T08:54:31Z

@PerfectSlayer Sure, just used sed 😉

Anyway, the debugger benchmarks will need to be checked, these results are weird.

jpbempel · 2024-11-25T15:24:01Z

The rule is kind of useless. even if append on char is marginally faster that string, before make it noticeable you need a very critical million iterations to see a difference, and most of the time on a constant.
I found those rules more counter-productive than relevant. just my 2 cents

smola · 2024-11-26T08:10:08Z

Ack. I'll merge this as a one-off, since they won't be harmful anyway.

smola added tag: no release notes Changes to exclude from release notes type: refactoring labels Nov 25, 2024

PerfectSlayer approved these changes Nov 25, 2024

View reviewed changes

PerfectSlayer reviewed Nov 25, 2024

View reviewed changes

Comment thread ...t/instrumentation/testng/src/main/java/datadog/trace/instrumentation/testng/TestNGUtils.java Outdated

Replace StringBuilder#append(String) with StringBuilder#append(char)

0fcd18e

smola force-pushed the smola/single-char branch from 5a15ca9 to 0fcd18e Compare November 25, 2024 09:45

smola marked this pull request as ready for review November 25, 2024 11:53

smola requested review from a team as code owners November 25, 2024 11:53

smola requested review from mcculls, nikita-tkachenko-datadog and shatzi and removed request for a team November 25, 2024 11:53

Merge branch 'master' into smola/single-char

7d452a8

smola merged commit 92e8023 into master Nov 26, 2024

smola deleted the smola/single-char branch November 26, 2024 08:10

github-actions Bot added this to the 1.44.0 milestone Nov 26, 2024

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Replace StringBuilder#append(String) with StringBuilder#append(char)#8008

Replace StringBuilder#append(String) with StringBuilder#append(char)#8008
smola merged 2 commits intomasterfrom
smola/single-char

smola commented Nov 25, 2024

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smola commented Nov 25, 2024

What Does This Do

Motivation

Additional Notes

Contributor Checklist

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Debugger benchmarks

Parameters

Summary

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Benchmarks

Startup

Load

Dacapo

Parameters

Summary

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smola commented Nov 25, 2024

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