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Add a flag to silence the error message for an out-of-date snapshot version #20784
Description
Activity
Could you consume the stderr, look for this warning, and if you see it, filter it and compensate (recompile) ?
Are you spawning the child process as an isolate or as a separate OS process?
Agreed, this would be a confusing message for the user.
Removed Priority-Unassigned label.
Added Priority-Low label.Could you consume the stderr, look for this warning, and if you see it, filter it and compensate (recompile) ?
Theoretically yes, but this would add a lot of complexity since we want to avoid getting in the way of child processes at all. We don't want to parse the output as a string since it may be binary data, so we'd have to match the raw bytes against some known prefix. We'd need to replay them if we found any that don't match the expected message from the VM or if the process exited with a non-VM exit code. All of this would have to be done in the face of potentially-arbitrary chunking of bytes.
Are you spawning the child process as an isolate or as a separate OS process?
The latter, although that's not set in stone.
Just ran stagehand, and got two scary messages:
sethladd@sethladd-macbookair ~/manyanonlibs $ stagehand package
Wrong script snapshot version, expected 'a10659e29cf9744e06a63bf183bc5c49' found 'd4922cb239c676d9d6f97ef6347fc02b'
Wrong script snapshot version, expected 'a10659e29cf9744e06a63bf183bc5c49' found 'd4922cb239c676d9d6f97ef6347fc02b'
Creating package application 'manyanonlibs':
/Users/sethladd/manyanonlibs/.gitignore
/Users/sethladd/manyanonlibs/CHANGELOG.md
/Users/sethladd/manyanonlibs/LICENSE
/Users/sethladd/manyanonlibs/README.md
/Users/sethladd/manyanonlibs/example/manyanonlibs.dart
/Users/sethladd/manyanonlibs/lib/manyanonlibs.dart
/Users/sethladd/manyanonlibs/lib/src/manyanonlibs_base.dart
/Users/sethladd/manyanonlibs/pubspec.yaml
/Users/sethladd/manyanonlibs/test/all_test.dart
9 files written.--> to provision required packages, run 'pub get'
Wondering what we can do to not print these two duplicate wrong script snapshot version messages?
Here's what the script looks like (which is created when pub globally activates a package aka installs the package globally)
#!/usr/bin/env sh
This file was created by pub v1.9.1.
Package: stagehand
Version: 0.1.5+4
Executable: stagehand
Script: stagehand
dart "/Users/sethladd/.pub-cache/global_packages/stagehand/bin/stagehand.dart.snapshot" "$@"
The VM exits with code 253 if the snapshot version is out-of-date.
If it is, we need to delete it and run "pub global" manually.
exit_code=$?
if [ $exit_code != 253 ]; then
exit $exit_code
fipub global run stagehand:stagehand "$@"
cc @a-siva.
Scenario A: stop creating snapshots. problem solved :)
Scenario B: pass something to the VM that says "please don't print out a snapshot version mismatch message"
Scenario C: consume all stderr with some wrapper script/shell-thing and filter out that message
Personally, I'm a fan of A, as it's the most simple solution. Thoughts?
cc @floitschG.
Snapshots are crucial for the performance of package executables, especially those that are the result of transformed code. Scenario A isn't an option, at least until the VM somehow gets to the point where it starts up equally fast on raw Dart code.
Scenario C would pose all the same semantic problems with wrapping that we're seeing with "pub run". As far as I know, there's no way to both capture a subprocess's stdout and still convince the subprocess that it's talking to a terminal.
Scenario B would work okay, but I'd prefer the solution outlined in issue #20802: passing a flag to the VM that causes it to just return an exit code for whether the snapshot is up to date without trying to run it at all. Not only would this be extremely simple, it would eliminate any possibility of the executable returning the same exit code that the VM uses to signal an invalid snapshot, which is a problem with the current setup and with Scenario B.
When "pub run" starts running the VM on a snapshot, it pipes the child process's stdout and stderr to the main process's streams. However, if the snapshot is out-of-date, this means that the user sees the "Wrong full snapshot version" message, which is confusing for them since pub otherwise silently handles snapshot recompilation.
It would be good if there were a flag that could be passed to the VM to disable this message.