VoskJS HTTPServer crash (v8::internal::GlobalBackingStoreRegistry::Register)

Hi Nicolay!

I'm working on VoskJs, a simple wrapper of nodejs Vosk binding, and I'm now released an HTTP server using last multi-threading features part of Vosk API. See: https://github.com/solyarisoftware/voskJs/blob/master/voskjs.js#L121

The draft HTTP server I implemented is very simple: it just takes HTTP POST /transcript requests, processing the speech file specified in the request body: https://github.com/solyarisoftware/voskJs/tree/master/examples#transcript-http-server

I want to stress test httpServer.js to monitor throughput and latencies, using an Apache Bench (ab) script:
https://github.com/solyarisoftware/voskJs/blob/master/tests/abtest.sh

Running the ab stress test, with by example 2 concurrent requests (for 500 times), the server run smoothly for a while (100/200 requests), consuming almost 2 cores (see pidstat logs here listed), but the server crashes after a while. See here below the stderr messages. BTW, rising the number of concurrent requests, the server crashes in a minor time.

Reading error:
```
3: 0x100c201 v8::internal::GlobalBackingStoreRegistry::Register(std::shared_ptr) [node]
```

It seems to me that the issue could maybe related to some memory node binding problem.

Any idea?
Please let me know if you need more info.

Thanks
Giorgio

---

**httpServer stderr**

```bash
$ pidstat 1 -u -e node httpServer > httpServer.log

#
# Fatal error in , line 0
# Check failed: result.second.
#
#
#
#FailureMessage Object: 0x7ffcaa9487e0
1: 0xb7db41 [node]
2: 0x1c15474 V8_Fatal(char const*, ...) [node]
3: 0x100c201 v8::internal::GlobalBackingStoreRegistry::Register(std::shared_ptr) [node]
4: 0xd23818 v8::ArrayBuffer::GetBackingStore() [node]
5: 0xacb640 napi_get_typedarray_info [node]
6: 0x7fb14c3a10ff [/home/giorgio/voskjs/node_modules/ref-napi/prebuilds/linux-x64/node.napi.node]
7: 0x7fb14c3a18a8 [/home/giorgio/voskjs/node_modules/ref-napi/prebuilds/linux-x64/node.napi.node]
8: 0x7fb14c3a3591 [/home/giorgio/voskjs/node_modules/ref-napi/prebuilds/linux-x64/node.napi.node]
9: 0x7fb14c3a9d6b Napi::details::CallbackData::Wrapper(napi_env__*, napi_callback_info__*) [/home/giorgio/voskjs/node_modules/ref-napi/prebuilds/linux-x64/node.napi.node]
10: 0xac220f [node]
11: 0xd5f70b [node]
12: 0xd60bac [node]
13: 0xd61226 v8::internal::Builtin_HandleApiCall(int, unsigned long*, v8::internal::Isolate*) [node]
14: 0x160c579 [node]
```

**Apache Bench test**

```bash
$ com/abtest.sh

test httpServer using apache bench
2 concurrent clients
500 requests to run

full ab command
ab -p /home/giorgio/voskjs/examples/com/body.json -T application/json -H 'Content-Type: application/json' -c 2 -n 500 -l -k -r http://localhost:3000/transcript

This is ApacheBench, Version 2.3 <$Revision: 1843412 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking localhost (be patient)
Completed 100 requests
Completed 200 requests
Completed 300 requests
Completed 400 requests
Completed 500 requests
Finished 500 requests

Server Software:
Server Hostname: localhost
Server Port: 3000

Document Path: /transcript
Document Length: Variable

Concurrency Level: 2
Time taken for tests: 27.141 seconds
Complete requests: 500
Failed requests: 660
(Connect: 0, Receive: 440, Length: 0, Exceptions: 220)
Keep-Alive requests: 0
Total transferred: 24973 bytes
Total body sent: 17080
HTML transferred: 18660 bytes
Requests per second: 18.42 [#/sec] (mean)
Time per request: 108.563 [ms] (mean)
Time per request: 54.282 [ms] (mean, across all concurrent requests)
Transfer rate: 0.90 [Kbytes/sec] received
0.61 kb/s sent
1.51 kb/s total

Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.0 0 0
Processing: 0 107 296.6 0 1214
Waiting: 0 103 288.8 0 1213
Total: 0 107 296.6 0 1214

Percentage of the requests served within a certain time (ms)
50% 0
66% 0
75% 0
80% 0
90% 739
95% 981
98% 1094
99% 1174
100% 1214 (longest request)
```

**httpServer.log** (excerpt)

```bash

Linux 5.8.0-50-generic (giorgio-HP-Laptop-17-by1xxx) 30/04/2021 _x86_64_ (8 CPU)
1619767436135 Press Ctrl-C to shutdown
1619767436136 Model directory: ../models/vosk-model-small-en-us-0.15
1619767436413 load model latency: 275ms
1619767436415 Server httpServer.js running at http://localhost:3000
1619767436415 Endpoint http://localhost:3000/transcript

09:23:55 UID PID %usr %system %guest %wait %CPU CPU Command
09:23:56 1000 45074 46,00 10,00 0,00 0,00 56,00 7 node
09:23:57 1000 45074 0,00 0,00 0,00 0,00 0,00 7 node
09:23:58 1000 45074 0,00 0,00 0,00 0,00 0,00 7 node
09:23:59 1000 45074 0,00 0,00 0,00 0,00 0,00 7 node
09:24:00 1000 45074 0,00 0,00 0,00 0,00 0,00 7 node
09:24:01 1000 45074 0,00 0,00 0,00 0,00 0,00 7 node
09:24:02 1000 45074 0,00 0,00 0,00 0,00 0,00 7 node
09:24:03 1000 45074 0,00 0,00 0,00 0,00 0,00 7 node
09:24:04 1000 45074 2,00 0,00 0,00 0,00 2,00 7 node
1619767445908 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

09:24:05 1000 45074 8,00 0,00 0,00 0,00 8,00 7 node
1619767446466 id 1619767445908 transcript latency 558ms
1619767446466 response id 1619767445908 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767445908,"latency":558,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767446470 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

1619767446526 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

09:24:06 1000 45074 139,00 2,00 0,00 0,00 141,00 7 node
1619767447189 id 1619767446470 transcript latency 719ms
1619767447189 response id 1619767446470 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767446470,"latency":719,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767447232 id 1619767446526 transcript latency 706ms
1619767447232 response id 1619767446526 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767446526,"latency":706,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767447233 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

1619767447288 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

1619767447954 id 1619767447288 transcript latency 666ms
1619767447954 response id 1619767447288 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767447288,"latency":666,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
09:24:07 1000 45074 176,00 0,00 0,00 0,00 176,00 7 node

1619767469520 id 1619767468466 transcript latency 1054ms
1619767469520 response id 1619767468466 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767468466,"latency":1054,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767469522 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

09:24:29 1000 45074 171,00 1,00 0,00 0,00 172,00 7 node
1619767470485 id 1619767469373 transcript latency 1111ms
1619767470485 response id 1619767469373 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767469373,"latency":1111,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767470546 id 1619767469522 transcript latency 1024ms
1619767470546 response id 1619767469522 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767469522,"latency":1024,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767470548 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

1619767470635 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

09:24:30 1000 45074 174,00 0,00 0,00 0,00 174,00 7 node
1619767471542 id 1619767470635 transcript latency 906ms
1619767471542 response id 1619767470635 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767470635,"latency":906,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767471601 id 1619767470548 transcript latency 1053ms
1619767471601 response id 1619767470548 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767470548,"latency":1053,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767471604 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

1619767471694 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

09:24:31 1000 45074 173,00 0,00 0,00 0,00 173,00 7 node
1619767472611 id 1619767471604 transcript latency 1007ms
1619767472611 response id 1619767471604 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767471604,"latency":1007,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767472672 id 1619767471694 transcript latency 978ms
1619767472672 response id 1619767471694 {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2","requestId":1619767471694,"latency":978,"result":[{"conf":1,"end":1.02,"start":0.36,"word":"experience"},{"conf":1,"end":1.35,"start":1.02,"word":"proves"},{"conf":1,"end":1.74,"start":1.35,"word":"this"}],"text":"experience proves this"}
1619767472674 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

1619767472764 request {"speech":"../audio/2830-3980-0043.wav","model":"vosk-model-en-us-aspire-0.2"}

09:24:32 1000 45074 149,00 1,00 0,00 0,00 150,00 0 node

Average: 1000 45074 127,76 0,73 0,00 0,00 128,49 - node