Flow: Flow crashes unpredictably on CircleCI

[jamesisaac]

Flow version:

• 0.88 and below: seems to work
• 0.89: _sometimes_ works
• 0.96 and 0.106.3: seems to always fail

Expected behavior

I have a fairly large project using React, Relay, and other libraries, and recently tried upgrading the Flow version from 0.86. Flow check works fine locally after the upgrade on Windows and Mac, so I would expect it to on CircleCI too.

Actual behavior

Trying to run a flow check on CircleCI (their circleci/node:12 image) causes it to continually crash and eventually give up. However, in my experiments with running the identical codebase on different versions of Flow, it sometimes was succeeding on CircleCI with Flow 0.89.0, sometimes crashing.

Workaround

After writing this issue out I've found some similar issues: #6242 and https://github.com/flowtype/flow-bin/issues/138 , which provided this workaround in .flowconfig which seems to solve it:

[options]
server.max_workers=4

Thought I might as well just post this anyway though to bring attention to this type of issue still existing today, and maybe help debug it.

Debug info

Pasting the contents below of the test output, .flowconfig, log, monitor_log, log.old, monitor_log.old from one of the crashing attempts on 0.106.3

test output:

yarn run v1.17.3
$ /home/circleci/app/node_modules/.bin/flow
Launching Flow server for /home/circleci/app
Spawned flow server (pid=96)
Logs will go to /tmp/flow/zShomezScirclecizSapp.log
Monitor logs will go to /tmp/flow/zShomezScirclecizSapp.monitor_log
Launching Flow server for /home/circleci/app
Spawned flow server (pid=204)
Logs will go to /tmp/flow/zShomezScirclecizSapp.log
Monitor logs will go to /tmp/flow/zShomezScirclecizSapp.monitor_log
Launching Flow server for /home/circleci/app
Spawned flow server (pid=316)
Logs will go to /tmp/flow/zShomezScirclecizSapp.log
Monitor logs will go to /tmp/flow/zShomezScirclecizSapp.monitor_log
Launching Flow server for /home/circleci/app
Spawned flow server (pid=425)
Logs will go to /tmp/flow/zShomezScirclecizSapp.log
Monitor logs will go to /tmp/flow/zShomezScirclecizSapp.monitor_log
Lost connection to the flow server (0 retries remaining): /Out of retries, exiting!
error Command failed with exit code 7.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
Exited with code 7

.flowconfig:

[ignore]

[include]

[libs]

[lints]

[options]
esproposal.optional_chaining=enable

[strict]

log:

[2019-09-02 11:43:30.555] argv=/home/circleci/app/node_modules/flow-bin/flow-linux64-v0.106.3/flow start --flowconfig-name .flowconfig --from parent cmdline: /usr/local/bin/node /home/circleci/app/node_modules/.bin/flow --temp-dir /tmp/flow /home/circleci/app
[2019-09-02 11:43:30.555] lazy_mode=off
[2019-09-02 11:43:30.555] arch=classic
[2019-09-02 11:43:30.555] abstract_locations=off
[2019-09-02 11:43:30.555] max_workers=36
[2019-09-02 11:43:30.646] Initializing Server (This might take some time)
[2019-09-02 11:43:30.646] executable=/home/circleci/app/node_modules/flow-bin/flow-linux64-v0.106.3/flow
[2019-09-02 11:43:30.646] version=0.106.3
[2019-09-02 11:43:30.647] No saved state available
[2019-09-02 11:43:30.647] Parsing
Worker interrupted with signal: sigkill
Worker interrupted with signal: sigkill
Worker interrupted with signal: sigkill
Worker interrupted with signal: sigkill
Subprocess(454): fail 2Unhandled exception: Worker_failed (process_id = 454): (Worker_quit WEXITED 2)
Raised at file "map.ml", line 135, characters 10-25
Called from file "hack/utils/collections/myMap.ml", line 15, characters 13-23
Re-raised at file "src/core/lwt.ml", line 2998, characters 20-29
Called from file "src/unix/lwt_main.ml", line 26, characters 8-18
Called from file "src/server/server.ml", line 220, characters 6-54

Worker slave 514 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 515 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 513 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 511 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 514 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 508 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 515 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 512 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 513 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 511 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 508 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 512 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 510 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 510 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 507 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 507 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 505 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 506 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 505 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 506 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 504 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 494 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 495 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 504 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 494 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 495 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 501 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 496 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 501 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 497 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 496 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 499 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 498 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 497 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 499 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 498 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 502 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 502 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 516 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 516 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 519 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 519 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 521 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 521 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 523 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 523 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 517 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 517 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 522 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 522 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 520 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 520 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 509 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 509 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 518 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 518 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

monitor_log:

Sep  2 11:43:30.463 [info] argv=/home/circleci/app/node_modules/flow-bin/flow-linux64-v0.106.3/flow start --flowconfig-name .flowconfig --from parent cmdline: /usr/local/bin/node /home/circleci/app/node_modules/.bin/flow --temp-dir /tmp/flow /home/circleci/app
Sep  2 11:43:30.463 [info] lazy_mode=off
Sep  2 11:43:30.463 [info] arch=classic
Sep  2 11:43:30.463 [info] abstract_locations=off
Sep  2 11:43:30.463 [info] max_workers=36
Sep  2 11:43:30.463 [info] Creating a new Flow server
Sep  2 11:43:41.759 [error] Connection 'server #1' was closed from the other side
dmesg: read kernel buffer failed: Operation not permitted
Sep  2 11:43:41.862 [error] Flow server (pid 428) exited with code Unknown_error (110)
Sep  2 11:43:41.862 [info] Monitor is exiting (Dying along with server)
Sep  2 11:43:41.862 [info] Broadcasting to threads and waiting 1 second for them to exit

log.old:

[2019-09-02 11:43:26.260] argv=/home/circleci/app/node_modules/flow-bin/flow-linux64-v0.106.3/flow start --flowconfig-name .flowconfig --from parent cmdline: /usr/local/bin/node /home/circleci/app/node_modules/.bin/flow --temp-dir /tmp/flow /home/circleci/app
[2019-09-02 11:43:26.260] lazy_mode=off
[2019-09-02 11:43:26.260] arch=classic
[2019-09-02 11:43:26.260] abstract_locations=off
[2019-09-02 11:43:26.260] max_workers=36
[2019-09-02 11:43:26.310] Initializing Server (This might take some time)
[2019-09-02 11:43:26.310] executable=/home/circleci/app/node_modules/flow-bin/flow-linux64-v0.106.3/flow
[2019-09-02 11:43:26.310] version=0.106.3
[2019-09-02 11:43:26.310] No saved state available
[2019-09-02 11:43:26.310] Parsing
Worker interrupted with signal: sigkill
Worker interrupted with signal: sigkill
Worker interrupted with signal: sigkill
Worker interrupted with signal: sigkill
Subprocess(338): fail 2Subprocess(345): fail 2Unhandled exception: Worker_failed (process_id = 338): (Worker_quit WEXITED 2)
Raised at file "map.ml", line 135, characters 10-25
Called from file "hack/utils/collections/myMap.ml", line 15, characters 13-23
Re-raised at file "src/core/lwt.ml", line 2998, characters 20-29
Called from file "src/unix/lwt_main.ml", line 26, characters 8-18
Called from file "src/server/server.ml", line 220, characters 6-54

Worker slave 404 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 403 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 404 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 402 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 401 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 405 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 403 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 402 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 401 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 398 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 400 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 405 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 398 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 400 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 395 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 395 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 396 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 397 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 396 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 397 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 382 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 394 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 383 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 382 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 384 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 385 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 394 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 383 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 384 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 385 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 391 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 388 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 391 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 386 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 388 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 389 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 387 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 390 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 386 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 389 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 387 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 390 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 392 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 392 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 406 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 406 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 409 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 409 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 411 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 411 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 407 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 407 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Worker slave 415 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 415 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 412 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 412 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 410 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 410 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Worker slave 399 exception: Unix.Unix_error(Unix.EPIPE, "write", "")
Worker slave 399 Potential backtrace:
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42
Unix.Unix_error(Unix.EPIPE, "write", "")
Raised by primitive operation at file "unix.ml", line 319, characters 7-34
Called from file "hack/utils/marshal_tools/marshal_tools.ml", line 82, characters 10-42

monitor_log.old:

Sep  2 11:43:26.169 [info] argv=/home/circleci/app/node_modules/flow-bin/flow-linux64-v0.106.3/flow start --flowconfig-name .flowconfig --from parent cmdline: /usr/local/bin/node /home/circleci/app/node_modules/.bin/flow --temp-dir /tmp/flow /home/circleci/app
Sep  2 11:43:26.170 [info] lazy_mode=off
Sep  2 11:43:26.170 [info] arch=classic
Sep  2 11:43:26.170 [info] abstract_locations=off
Sep  2 11:43:26.170 [info] max_workers=36
Sep  2 11:43:26.170 [info] Creating a new Flow server
Sep  2 11:43:29.962 [error] Connection 'server #1' was closed from the other side
[2019-09-02 11:43:29.963] Uncaught async exception. Exiting
    Exception: (Failure "Dfind was not initialized")
    Backtrace:
        Raised at file "map.ml", line 135, characters 10-25
        Called from file "src/core/lwt.ml", line 796, characters 20-60
Uncaught async exception: (Failure "Dfind was not initialized")
Raised at file "map.ml", line 135, characters 10-25
Called from file "src/core/lwt.ml", line 796, characters 20-60

[kevinbarabash]

When running on CI you may want to run flow check --max-workers 4 that way you don't have to modify your .flowconfig. I use --max-workers 0 for most of my projects since I'm on the free tier of Circle CI.

[trymbill]

Thank you for posting the workaround, saved me a few hours!