events: improve events performance by rluvaton · Pull Request #50422 · nodejs/node · GitHub

Benchmarks

Change _events to be a Map:

Notes:

I'm afraid this can break userland implementation of EventEmitter that are using node EventEmitter class functions (cc @ronag )
This also improves creation by a lot (and therefore improves streams creation)

15:31:01                                                                  confidence improvement accuracy (*)    (**)   (***)
15:31:01 events/ee-add-remove.js n=1000000 removeListener=0 newListener=0        ***     19.64 %       ±1.57%  ±2.09%  ±2.73%
15:31:01 events/ee-add-remove.js n=1000000 removeListener=0 newListener=1        ***     46.84 %       ±2.02%  ±2.70%  ±3.54%
15:31:01 events/ee-add-remove.js n=1000000 removeListener=1 newListener=0        ***     45.01 %       ±2.68%  ±3.60%  ±4.75%
15:31:01 events/ee-add-remove.js n=1000000 removeListener=1 newListener=1        ***     56.27 %       ±2.72%  ±3.64%  ±4.79%
15:31:01 events/ee-emit.js listeners=1 argc=0 n=2000000                          ***     32.42 %       ±9.82% ±13.07% ±17.02%
15:31:01 events/ee-emit.js listeners=1 argc=10 n=2000000                         ***     36.00 %       ±8.08% ±10.75% ±14.00%
15:31:01 events/ee-emit.js listeners=1 argc=2 n=2000000                          ***     23.57 %       ±9.57% ±12.75% ±16.62%
15:31:01 events/ee-emit.js listeners=1 argc=4 n=2000000                          ***     28.33 %       ±8.95% ±11.92% ±15.52%
15:31:01 events/ee-emit.js listeners=10 argc=0 n=2000000                                  4.48 %       ±7.03%  ±9.35% ±12.17%
15:31:01 events/ee-emit.js listeners=10 argc=10 n=2000000                                 0.02 %       ±4.28%  ±5.70%  ±7.42%
15:31:01 events/ee-emit.js listeners=10 argc=2 n=2000000                          **     -6.22 %       ±4.54%  ±6.06%  ±7.91%
15:31:01 events/ee-emit.js listeners=10 argc=4 n=2000000                          **      6.55 %       ±4.59%  ±6.13%  ±8.00%
15:31:01 events/ee-emit.js listeners=5 argc=0 n=2000000                                   1.39 %       ±9.30% ±12.37% ±16.11%
15:31:01 events/ee-emit.js listeners=5 argc=10 n=2000000                                 -0.34 %       ±7.02%  ±9.35% ±12.18%
15:31:01 events/ee-emit.js listeners=5 argc=2 n=2000000                                   5.45 %       ±8.85% ±11.78% ±15.33%
15:31:01 events/ee-emit.js listeners=5 argc=4 n=2000000                                   0.79 %       ±8.60% ±11.44% ±14.89%
15:31:01 events/ee-listen-unique.js n=1000000 events=1                           ***     30.56 %       ±2.05%  ±2.73%  ±3.56%
15:31:01 events/ee-listen-unique.js n=1000000 events=10                          ***     13.34 %       ±1.21%  ±1.62%  ±2.11%
15:31:01 events/ee-listen-unique.js n=1000000 events=2                           ***     18.32 %       ±1.99%  ±2.67%  ±3.51%
15:31:01 events/ee-listen-unique.js n=1000000 events=20                          ***     13.37 %       ±1.22%  ±1.62%  ±2.12%
15:31:01 events/ee-listen-unique.js n=1000000 events=3                           ***     19.46 %       ±1.15%  ±1.53%  ±2.00%
15:31:01 events/ee-listen-unique.js n=1000000 events=5                           ***     15.05 %       ±1.35%  ±1.80%  ±2.35%
15:31:01 events/ee-listener-count-on-prototype.js n=50000000                     ***     29.98 %       ±5.74%  ±7.70% ±10.14%
15:31:01 events/ee-listeners.js raw='false' listeners=5 n=5000000                        -2.69 %       ±7.61% ±10.13% ±13.18%
15:31:01 events/ee-listeners.js raw='false' listeners=50 n=5000000                        0.48 %       ±1.82%  ±2.42%  ±3.15%
15:31:01 events/ee-listeners.js raw='true' listeners=5 n=5000000                          6.34 %       ±8.35% ±11.12% ±14.49%
15:31:01 events/ee-listeners.js raw='true' listeners=50 n=5000000                        -1.34 %       ±4.45%  ±5.92%  ±7.71%
15:31:01 events/ee-once.js argc=0 n=20000000                                     ***     31.26 %       ±1.10%  ±1.47%  ±1.94%
15:31:01 events/ee-once.js argc=1 n=20000000                                     ***     26.62 %       ±0.60%  ±0.80%  ±1.04%
15:31:01 events/ee-once.js argc=4 n=20000000                                     ***     26.93 %       ±0.65%  ±0.86%  ±1.12%
15:31:01 events/ee-once.js argc=5 n=20000000                                     ***     27.19 %       ±0.76%  ±1.02%  ±1.32%
15:31:01 events/eventtarget-add-remove.js nListener=10 n=1000000                 ***      0.92 %       ±0.38%  ±0.51%  ±0.66%
15:31:01 events/eventtarget-add-remove.js nListener=5 n=1000000                    *      0.87 %       ±0.69%  ±0.91%  ±1.19%
15:31:01 events/eventtarget-creation.js n=1000000                                         0.60 %       ±5.04%  ±6.70%  ±8.73%
15:31:01 events/eventtarget.js listeners=1 n=1000000                                      0.90 %       ±6.28%  ±8.35% ±10.87%
15:31:01 events/eventtarget.js listeners=10 n=1000000                                     0.45 %       ±3.51%  ±4.68%  ±6.09%
15:31:01 events/eventtarget.js listeners=5 n=1000000                                      0.21 %       ±4.80%  ±6.39%  ±8.31%
15:31:01 
15:31:01 Be aware that when doing many comparisons the risk of a false-positive
15:31:01 result increases. In this case, there are 37 comparisons, you can thus
15:31:01 expect the following amount of false-positive results:
15:31:01   1.85 false positives, when considering a   5% risk acceptance (*, **, ***),
15:31:01   0.37 false positives, when considering a   1% risk acceptance (**, ***),
15:31:01   0.04 false positives, when considering a 0.1% risk acceptance (***)

I run it on streams as well to see the impact as this was my original intent: url

Change to Map todos:

move all our internal code away from _events and use [kEvents] instead
I saw undici used _events so need to migrate as well

change _events to be without __proto__: null

change _events to be without proto: null

Commit: eb29e97

I think the performance without proto is not fully representative as the event name can be anything so the dictionary mode is not used here

Benchmark URL

12:55:39 ++ Rscript benchmark/compare.R
12:55:40                                                                  confidence improvement accuracy (*)    (**)   (***)
12:55:40 events/ee-add-remove.js n=1000000 removeListener=0 newListener=0         **     -2.22 %       ±1.50%  ±2.00%  ±2.60%
12:55:40 events/ee-add-remove.js n=1000000 removeListener=0 newListener=1        ***     30.34 %       ±1.75%  ±2.33%  ±3.04%
12:55:40 events/ee-add-remove.js n=1000000 removeListener=1 newListener=0        ***     22.74 %       ±1.17%  ±1.56%  ±2.03%
12:55:40 events/ee-add-remove.js n=1000000 removeListener=1 newListener=1        ***     10.04 %       ±1.11%  ±1.47%  ±1.92%
12:55:40 events/ee-emit.js listeners=1 argc=0 n=2000000                          ***    159.54 %       ±8.72% ±11.64% ±15.20%
12:55:40 events/ee-emit.js listeners=1 argc=10 n=2000000                         ***    139.14 %      ±12.44% ±16.59% ±21.66%
12:55:40 events/ee-emit.js listeners=1 argc=2 n=2000000                          ***    159.56 %      ±13.83% ±18.46% ±24.15%
12:55:40 events/ee-emit.js listeners=1 argc=4 n=2000000                          ***    148.52 %      ±10.04% ±13.37% ±17.43%
12:55:40 events/ee-emit.js listeners=10 argc=0 n=2000000                         ***     13.34 %       ±7.48%  ±9.96% ±12.96%
12:55:40 events/ee-emit.js listeners=10 argc=10 n=2000000                        ***     11.22 %       ±5.66%  ±7.53%  ±9.81%
12:55:40 events/ee-emit.js listeners=10 argc=2 n=2000000                                  3.11 %       ±6.21%  ±8.27% ±10.77%
12:55:40 events/ee-emit.js listeners=10 argc=4 n=2000000                         ***     12.07 %       ±6.04%  ±8.04% ±10.47%
12:55:40 events/ee-emit.js listeners=5 argc=0 n=2000000                          ***     20.76 %       ±9.34% ±12.44% ±16.24%
12:55:40 events/ee-emit.js listeners=5 argc=10 n=2000000                         ***     17.29 %       ±8.71% ±11.59% ±15.10%
12:55:40 events/ee-emit.js listeners=5 argc=2 n=2000000                            *     13.10 %       ±9.93% ±13.21% ±17.20%
12:55:40 events/ee-emit.js listeners=5 argc=4 n=2000000                            *      9.82 %       ±9.51% ±12.66% ±16.48%
12:55:40 events/ee-listen-unique.js n=1000000 events=1                                    0.24 %       ±1.32%  ±1.76%  ±2.29%
12:55:40 events/ee-listen-unique.js n=1000000 events=10                          ***     -3.02 %       ±1.08%  ±1.44%  ±1.88%
12:55:40 events/ee-listen-unique.js n=1000000 events=2                           ***     -2.28 %       ±0.69%  ±0.92%  ±1.20%
12:55:40 events/ee-listen-unique.js n=1000000 events=20                           **     -2.16 %       ±1.56%  ±2.09%  ±2.73%
12:55:40 events/ee-listen-unique.js n=1000000 events=3                           ***     -2.03 %       ±0.98%  ±1.31%  ±1.71%
12:55:40 events/ee-listen-unique.js n=1000000 events=5                           ***     -4.36 %       ±0.89%  ±1.19%  ±1.55%
12:55:40 events/ee-listener-count-on-prototype.js n=50000000                     ***     -6.40 %       ±3.40%  ±4.53%  ±5.91%
12:55:40 events/ee-listeners.js raw='false' listeners=5 n=5000000                  *     -8.30 %       ±6.34%  ±8.45% ±11.02%
12:55:40 events/ee-listeners.js raw='false' listeners=50 n=5000000                       -1.08 %       ±1.71%  ±2.28%  ±2.97%
12:55:40 events/ee-listeners.js raw='true' listeners=5 n=5000000                         -3.00 %       ±5.69%  ±7.58%  ±9.89%
12:55:40 events/ee-listeners.js raw='true' listeners=50 n=5000000                         3.68 %       ±4.65%  ±6.18%  ±8.05%
12:55:40 events/ee-once.js argc=0 n=20000000                                             -0.21 %       ±0.64%  ±0.85%  ±1.10%
12:55:40 events/ee-once.js argc=1 n=20000000                                              0.06 %       ±0.44%  ±0.59%  ±0.76%
12:55:40 events/ee-once.js argc=4 n=20000000                                             -0.13 %       ±0.62%  ±0.83%  ±1.08%
12:55:40 events/ee-once.js argc=5 n=20000000                                              0.26 %       ±0.69%  ±0.91%  ±1.19%
12:55:40 events/eventtarget-add-remove.js nListener=10 n=1000000                  **      0.71 %       ±0.42%  ±0.56%  ±0.73%
12:55:40 events/eventtarget-add-remove.js nListener=5 n=1000000                           0.30 %       ±0.70%  ±0.94%  ±1.22%
12:55:40 events/eventtarget-creation.js n=1000000                                         1.95 %       ±3.80%  ±5.09%  ±6.72%
12:55:40 events/eventtarget.js listeners=1 n=1000000                                     -0.66 %       ±5.51%  ±7.34%  ±9.55%
12:55:40 events/eventtarget.js listeners=10 n=1000000                                    -0.32 %       ±3.15%  ±4.19%  ±5.46%
12:55:40 events/eventtarget.js listeners=5 n=1000000                                     -0.39 %       ±5.18%  ±6.90%  ±8.98%
12:55:40 
12:55:40 Be aware that when doing many comparisons the risk of a false-positive
12:55:40 result increases. In this case, there are 37 comparisons, you can thus
12:55:40 expect the following amount of false-positive results:
12:55:40   1.85 false positives, when considering a   5% risk acceptance (*, **, ***),
12:55:40   0.37 false positives, when considering a   1% risk acceptance (**, ***),
12:55:40   0.04 false positives, when considering a 0.1% risk acceptance (***)

CI: https://ci.nodejs.org/job/node-test-pull-request/55268/

This is probably going to break someone somewhere. That being said, maybe there is a way to minimize it by returning a Proxy from the _events getter that more accurately imitates the original behavior.

Also, I'm surprised this is so much faster. Often the same events are used (e.g. for streams), so I would assume that V8 uses a shape rather than a map behind the scenes, which should be faster than a Map instance. @benjamingr wdyt?

I'm actually not that interested in ee-listen-unique and ee-once.

Also, I'm surprised this is so much faster. Often the same events are used (e.g. for streams), so I would assume that V8 uses a shape rather than a map behind the scenes, which should be faster than a Map instance.

{ __proto__: null } hint v8 to use the dictionary mode src/runtime/runtime-literals.cc in V8 (founded by @benjamingr)

This is probably going to break someone somewhere. That being said, maybe there is a way to minimize it by returning a Proxy from the _events getter that more accurately imitates the original behavior.

Often the same events are used (e.g. for streams)

you can see the results when removing __proto__ null at the bottom (collapsed)

This is concerning:

16:57:40                                                                                          confidence improvement accuracy (*)   (**)   (***)
16:57:40 streams/creation.js kind='duplex' n=50000000                                                     **      1.61 %       ±0.93% ±1.23%  ±1.61%
16:57:40 streams/creation.js kind='readable' n=50000000                                                  ***    -17.07 %       ±0.68% ±0.91%  ±1.19%
16:57:40 streams/creation.js kind='transform' n=50000000                                                 ***     24.20 %       ±1.46% ±1.95%  ±2.55%
16:57:40 streams/creation.js kind='writable' n=50000000                                                           0.54 %       ±0.92% ±1.23%  ±1.60%
16:57:40 streams/destroy.js kind='duplex' n=1000000                                                       **     -3.85 %       ±2.25% ±2.99%  ±3.90%
16:57:40 streams/destroy.js kind='readable' n=1000000                                                            -0.90 %       ±1.66% ±2.21%  ±2.88%
16:57:40 streams/destroy.js kind='transform' n=1000000                                                           -1.38 %       ±1.91% ±2.54%  ±3.31%
16:57:40 streams/destroy.js kind='writable' n=1000000                                                            -2.12 %       ±2.19% ±2.91%  ±3.80%
16:57:40 streams/pipe-object-mode.js n=5000000                                                             *      6.22 %       ±5.34% ±7.11%  ±9.26%
16:57:40 streams/pipe.js n=5000000                                                                       ***      7.73 %       ±3.87% ±5.15%  ±6.70%
16:57:40 streams/readable-async-iterator.js sync='no' n=100000                                                   -2.28 %       ±6.37% ±8.48% ±11.05%
16:57:40 streams/readable-async-iterator.js sync='yes' n=100000                                                  -0.80 %       ±5.49% ±7.30%  ±9.51%
16:57:40 streams/readable-bigread.js n=1000                                                                *      3.49 %       ±2.92% ±3.92%  ±5.17%
16:57:40 streams/readable-bigunevenread.js n=1000                                                                -0.62 %       ±3.22% ±4.33%  ±5.72%
16:57:40 streams/readable-boundaryread.js type='buffer' n=2000                                           ***     11.62 %       ±1.13% ±1.50%  ±1.95%
16:57:40 streams/readable-boundaryread.js type='string' n=2000                                                    2.67 %       ±3.46% ±4.61%  ±6.03%
16:57:40 streams/readable-from.js type='array' n=10000000                                                         4.68 %       ±5.29% ±7.05%  ±9.18%
16:57:40 streams/readable-from.js type='async-generator' n=10000000                                      ***      2.44 %       ±0.90% ±1.20%  ±1.56%
16:57:40 streams/readable-from.js type='sync-generator-with-async-values' n=10000000                     ***      4.27 %       ±0.99% ±1.32%  ±1.71%
16:57:40 streams/readable-from.js type='sync-generator-with-sync-values' n=10000000                               2.93 %       ±4.20% ±5.59%  ±7.28%
16:57:40 streams/readable-readall.js n=5000                                                                      -1.18 %       ±6.06% ±8.06% ±10.50%
16:57:40 streams/readable-unevenread.js n=1000                                                           ***      3.97 %       ±2.02% ±2.68%  ±3.49%
16:57:40 streams/writable-manywrites.js len=1024 callback='no' writev='no' sync='no' n=100000            ***     -3.08 %       ±1.04% ±1.38%  ±1.79%
16:57:40 streams/writable-manywrites.js len=1024 callback='no' writev='no' sync='yes' n=100000                    0.94 %       ±1.97% ±2.63%  ±3.43%
16:57:40 streams/writable-manywrites.js len=1024 callback='no' writev='yes' sync='no' n=100000           ***     -6.76 %       ±2.49% ±3.34%  ±4.39%
16:57:40 streams/writable-manywrites.js len=1024 callback='no' writev='yes' sync='yes' n=100000                  -3.66 %       ±4.38% ±5.84%  ±7.63%
16:57:40 streams/writable-manywrites.js len=1024 callback='yes' writev='no' sync='no' n=100000                   -2.13 %       ±3.01% ±4.01%  ±5.22%
16:57:40 streams/writable-manywrites.js len=1024 callback='yes' writev='no' sync='yes' n=100000                  -1.16 %       ±2.15% ±2.86%  ±3.72%
16:57:40 streams/writable-manywrites.js len=1024 callback='yes' writev='yes' sync='no' n=100000          ***     -4.85 %       ±2.67% ±3.56%  ±4.66%
16:57:40 streams/writable-manywrites.js len=1024 callback='yes' writev='yes' sync='yes' n=100000                 -1.77 %       ±3.70% ±4.95%  ±6.49%
16:57:40 streams/writable-manywrites.js len=32768 callback='no' writev='no' sync='no' n=100000                    0.89 %       ±3.28% ±4.39%  ±5.76%
16:57:40 streams/writable-manywrites.js len=32768 callback='no' writev='no' sync='yes' n=100000                  -1.94 %       ±3.64% ±4.85%  ±6.31%
16:57:40 streams/writable-manywrites.js len=32768 callback='no' writev='yes' sync='no' n=100000            *     -1.35 %       ±1.11% ±1.47%  ±1.92%
16:57:40 streams/writable-manywrites.js len=32768 callback='no' writev='yes' sync='yes' n=100000                 -2.63 %       ±3.85% ±5.12%  ±6.67%
16:57:40 streams/writable-manywrites.js len=32768 callback='yes' writev='no' sync='no' n=100000                   1.63 %       ±3.13% ±4.19%  ±5.53%
16:57:40 streams/writable-manywrites.js len=32768 callback='yes' writev='no' sync='yes' n=100000                 -1.37 %       ±2.82% ±3.75%  ±4.89%
16:57:40 streams/writable-manywrites.js len=32768 callback='yes' writev='yes' sync='no' n=100000          **     -1.50 %       ±1.09% ±1.44%  ±1.88%
16:57:40 streams/writable-manywrites.js len=32768 callback='yes' writev='yes' sync='yes' n=100000                -1.05 %       ±2.24% ±2.98%  ±3.88%
16:57:40 
16:57:40 Be aware that when doing many comparisons the risk of a false-positive
16:57:40 result increases. In this case, there are 38 comparisons, you can thus
16:57:40 expect the following amount of false-positive results:
16:57:40   1.90 false positives, when considering a   5% risk acceptance (*, **, ***),
16:57:40   0.38 false positives, when considering a   1% risk acceptance (**, ***),
16:57:40   0.04 false positives, when considering a 0.1% risk acceptance (***)

This is neat but I don't understand how it's faster since objects in dictionary mode and maps have basically the same performance.

Also the "polyfill" for ._eventsis incorrect since if someone sets a value on it it won't get reflected in the emitter.

{ proto: null } hint v8 to use the dictionary mod

What happens if you remove that hint? Sorry it's a bit unclear what your last benchmark results are from.

Also the "polyfill" for ._eventsis incorrect since if someone sets a value on it it won't get reflected in the emitter.

I know I still have a todo there to convert to Proxy so it support everything

This is neat but I don't understand how it's faster since objects in dictionary mode and maps have basically the same performance.

Maybe because it by default go to the dict mode?

{ proto: null } hint v8 to use the dictionary mod

What happens if you remove that hint? Sorry it's a bit unclear what your last benchmark results are from.

the benchmarks are from the linked commit

change _events to be without proto: null

Commit: eb29e97

I think the performance without proto is not fully representative as the event name can be anything so the dictionary mode is not used here

Benchmark URL

12:55:39 ++ Rscript benchmark/compare.R
12:55:40                                                                  confidence improvement accuracy (*)    (**)   (***)
12:55:40 events/ee-add-remove.js n=1000000 removeListener=0 newListener=0         **     -2.22 %       ±1.50%  ±2.00%  ±2.60%
12:55:40 events/ee-add-remove.js n=1000000 removeListener=0 newListener=1        ***     30.34 %       ±1.75%  ±2.33%  ±3.04%
12:55:40 events/ee-add-remove.js n=1000000 removeListener=1 newListener=0        ***     22.74 %       ±1.17%  ±1.56%  ±2.03%
12:55:40 events/ee-add-remove.js n=1000000 removeListener=1 newListener=1        ***     10.04 %       ±1.11%  ±1.47%  ±1.92%
12:55:40 events/ee-emit.js listeners=1 argc=0 n=2000000                          ***    159.54 %       ±8.72% ±11.64% ±15.20%
12:55:40 events/ee-emit.js listeners=1 argc=10 n=2000000                         ***    139.14 %      ±12.44% ±16.59% ±21.66%
12:55:40 events/ee-emit.js listeners=1 argc=2 n=2000000                          ***    159.56 %      ±13.83% ±18.46% ±24.15%
12:55:40 events/ee-emit.js listeners=1 argc=4 n=2000000                          ***    148.52 %      ±10.04% ±13.37% ±17.43%
12:55:40 events/ee-emit.js listeners=10 argc=0 n=2000000                         ***     13.34 %       ±7.48%  ±9.96% ±12.96%
12:55:40 events/ee-emit.js listeners=10 argc=10 n=2000000                        ***     11.22 %       ±5.66%  ±7.53%  ±9.81%
12:55:40 events/ee-emit.js listeners=10 argc=2 n=2000000                                  3.11 %       ±6.21%  ±8.27% ±10.77%
12:55:40 events/ee-emit.js listeners=10 argc=4 n=2000000                         ***     12.07 %       ±6.04%  ±8.04% ±10.47%
12:55:40 events/ee-emit.js listeners=5 argc=0 n=2000000                          ***     20.76 %       ±9.34% ±12.44% ±16.24%
12:55:40 events/ee-emit.js listeners=5 argc=10 n=2000000                         ***     17.29 %       ±8.71% ±11.59% ±15.10%
12:55:40 events/ee-emit.js listeners=5 argc=2 n=2000000                            *     13.10 %       ±9.93% ±13.21% ±17.20%
12:55:40 events/ee-emit.js listeners=5 argc=4 n=2000000                            *      9.82 %       ±9.51% ±12.66% ±16.48%
12:55:40 events/ee-listen-unique.js n=1000000 events=1                                    0.24 %       ±1.32%  ±1.76%  ±2.29%
12:55:40 events/ee-listen-unique.js n=1000000 events=10                          ***     -3.02 %       ±1.08%  ±1.44%  ±1.88%
12:55:40 events/ee-listen-unique.js n=1000000 events=2                           ***     -2.28 %       ±0.69%  ±0.92%  ±1.20%
12:55:40 events/ee-listen-unique.js n=1000000 events=20                           **     -2.16 %       ±1.56%  ±2.09%  ±2.73%
12:55:40 events/ee-listen-unique.js n=1000000 events=3                           ***     -2.03 %       ±0.98%  ±1.31%  ±1.71%
12:55:40 events/ee-listen-unique.js n=1000000 events=5                           ***     -4.36 %       ±0.89%  ±1.19%  ±1.55%
12:55:40 events/ee-listener-count-on-prototype.js n=50000000                     ***     -6.40 %       ±3.40%  ±4.53%  ±5.91%
12:55:40 events/ee-listeners.js raw='false' listeners=5 n=5000000                  *     -8.30 %       ±6.34%  ±8.45% ±11.02%
12:55:40 events/ee-listeners.js raw='false' listeners=50 n=5000000                       -1.08 %       ±1.71%  ±2.28%  ±2.97%
12:55:40 events/ee-listeners.js raw='true' listeners=5 n=5000000                         -3.00 %       ±5.69%  ±7.58%  ±9.89%
12:55:40 events/ee-listeners.js raw='true' listeners=50 n=5000000                         3.68 %       ±4.65%  ±6.18%  ±8.05%
12:55:40 events/ee-once.js argc=0 n=20000000                                             -0.21 %       ±0.64%  ±0.85%  ±1.10%
12:55:40 events/ee-once.js argc=1 n=20000000                                              0.06 %       ±0.44%  ±0.59%  ±0.76%
12:55:40 events/ee-once.js argc=4 n=20000000                                             -0.13 %       ±0.62%  ±0.83%  ±1.08%
12:55:40 events/ee-once.js argc=5 n=20000000                                              0.26 %       ±0.69%  ±0.91%  ±1.19%
12:55:40 events/eventtarget-add-remove.js nListener=10 n=1000000                  **      0.71 %       ±0.42%  ±0.56%  ±0.73%
12:55:40 events/eventtarget-add-remove.js nListener=5 n=1000000                           0.30 %       ±0.70%  ±0.94%  ±1.22%
12:55:40 events/eventtarget-creation.js n=1000000                                         1.95 %       ±3.80%  ±5.09%  ±6.72%
12:55:40 events/eventtarget.js listeners=1 n=1000000                                     -0.66 %       ±5.51%  ±7.34%  ±9.55%
12:55:40 events/eventtarget.js listeners=10 n=1000000                                    -0.32 %       ±3.15%  ±4.19%  ±5.46%
12:55:40 events/eventtarget.js listeners=5 n=1000000                                     -0.39 %       ±5.18%  ±6.90%  ±8.98%
12:55:40 
12:55:40 Be aware that when doing many comparisons the risk of a false-positive
12:55:40 result increases. In this case, there are 37 comparisons, you can thus
12:55:40 expect the following amount of false-positive results:
12:55:40   1.85 false positives, when considering a   5% risk acceptance (*, **, ***),
12:55:40   0.37 false positives, when considering a   1% risk acceptance (**, ***),
12:55:40   0.04 false positives, when considering a 0.1% risk acceptance (***)

change _events to be without proto: null

Looks great to me!

Also what about something like the following for streams?

diff --git a/lib/internal/streams/duplex.js b/lib/internal/streams/duplex.js
index 834d875be6..2b3fe64df9 100644
--- a/lib/internal/streams/duplex.js
+++ b/lib/internal/streams/duplex.js
@@ -63,6 +63,21 @@ function Duplex(options) {
   if (!(this instanceof Duplex))
     return new Duplex(options);
 
+  this._events = {
+    close: undefined,
+    error: undefined,
+    prefinish: undefined,
+    finish: undefined,
+    drain: undefined,
+    data: undefined,
+    end: undefined,
+    pause: undefined,
+    resume: undefined,
+    readable: undefined,
+    pipe: undefined,
+    unpipe: undefined,
+  };
+
   this._readableState = new Readable.ReadableState(options, this, true);
   this._writableState = new Writable.WritableState(options, this, true);
 
diff --git a/lib/internal/streams/readable.js b/lib/internal/streams/readable.js
index 80798a35dc..83f09194a6 100644
--- a/lib/internal/streams/readable.js
+++ b/lib/internal/streams/readable.js
@@ -316,6 +316,18 @@ function Readable(options) {
   if (!(this instanceof Readable))
     return new Readable(options);
 
+  this._events = {
+    close: undefined,
+    error: undefined,
+    data: undefined,
+    end: undefined,
+    pause: undefined,
+    resume: undefined,
+    readable: undefined,
+    pipe: undefined,
+    unpipe: undefined,
+  };
+
   this._readableState = new ReadableState(options, this, false);
 
   if (options) {
diff --git a/lib/internal/streams/writable.js b/lib/internal/streams/writable.js
index 74573033ea..69fb2be7f0 100644
--- a/lib/internal/streams/writable.js
+++ b/lib/internal/streams/writable.js
@@ -382,6 +382,14 @@ function Writable(options) {
   if (!(this instanceof Writable))
     return new Writable(options);
 
+    this._events = {
+      close: undefined,
+      error: undefined,
+      prefinish: undefined,
+      finish: undefined,
+      drain: undefined,
+    };
+
   this._writableState = new WritableState(options, this, false);
 
   if (options) {

Do you think it's representative, I think the reason someone put __proto__ null was to be in dict mode

Also what about something like the following for streams?

diff --git a/lib/internal/streams/duplex.js b/lib/internal/streams/duplex.js
index 834d875be6..2b3fe64df9 100644
--- a/lib/internal/streams/duplex.js
+++ b/lib/internal/streams/duplex.js
@@ -63,6 +63,21 @@ function Duplex(options) {
   if (!(this instanceof Duplex))
     return new Duplex(options);
 
+  this._events = {
+    close: undefined,
+    error: undefined,
+    prefinish: undefined,
+    finish: undefined,
+    drain: undefined,
+    data: undefined,
+    end: undefined,
+    pause: undefined,
+    resume: undefined,
+    readable: undefined,
+    pipe: undefined,
+    unpipe: undefined,
+  };
+
   this._readableState = new Readable.ReadableState(options, this, true);
   this._writableState = new Writable.WritableState(options, this, true);
 
diff --git a/lib/internal/streams/readable.js b/lib/internal/streams/readable.js
index 80798a35dc..83f09194a6 100644
--- a/lib/internal/streams/readable.js
+++ b/lib/internal/streams/readable.js
@@ -316,6 +316,18 @@ function Readable(options) {
   if (!(this instanceof Readable))
     return new Readable(options);
 
+  this._events = {
+    close: undefined,
+    error: undefined,
+    data: undefined,
+    end: undefined,
+    pause: undefined,
+    resume: undefined,
+    readable: undefined,
+    pipe: undefined,
+    unpipe: undefined,
+  };
+
   this._readableState = new ReadableState(options, this, false);
 
   if (options) {
diff --git a/lib/internal/streams/writable.js b/lib/internal/streams/writable.js
index 74573033ea..69fb2be7f0 100644
--- a/lib/internal/streams/writable.js
+++ b/lib/internal/streams/writable.js
@@ -382,6 +382,14 @@ function Writable(options) {
   if (!(this instanceof Writable))
     return new Writable(options);
 
+    this._events = {
+      close: undefined,
+      error: undefined,
+      prefinish: undefined,
+      finish: undefined,
+      drain: undefined,
+    };
+
   this._writableState = new WritableState(options, this, false);
 
   if (options) {

I thought about that, but since I changed to Map I did not do it

Eh, this makes one use case slower and another one faster (changing to no proto: null), making "EventEmitter events shape specific to common use cases for streams" could be worth it, with benchmarks

Possible duplicate of #44627 and #39939. See also #11930.

Supersede by #50428

events: improve creation performance

eb29e97

nodejs-github-bot added events Issues and PRs related to the events subsystem / EventEmitter. needs-ci PRs that need a full CI run. labels Oct 27, 2023

rluvaton changed the title events: improve creation performance events: improve events performance Oct 27, 2023

rluvaton force-pushed the improve-ee-creation branch from 4c02bdb to bb44f6f Compare October 27, 2023 10:11

rluvaton added the performance Issues and PRs related to the performance of Node.js. label Oct 27, 2023

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events: replace _events with Map

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rluvaton force-pushed the improve-ee-creation branch from bb44f6f to 249c2b8 Compare October 27, 2023 10:51

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events: remove __proto__ null from _events

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rluvaton deleted the improve-ee-creation branch October 29, 2023 10:21

events: improve events performance by rluvaton · Pull Request #50422 · nodejs/node · GitHub

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events: improve events performance - #50422

events: improve events performance#50422rluvaton wants to merge 3 commits intonodejs:mainnodejs/node:mainfrom rluvaton:improve-ee-creationrluvaton/node:improve-ee-creationCopy head branch name to clipboard

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rluvaton commented Oct 27, 2023 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Benchmarks

Change _events to be a Map:

Change to Map todos:

change _events to be without __proto__: null

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change _events to be without __proto__: null

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events: improve events performance#50422
rluvaton wants to merge 3 commits into
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rluvaton:improve-ee-creation

rluvaton commented Oct 27, 2023 •
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change _events to be without proto: null

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change _events to be without proto: null