From @smls

Golfed program to demonstrate the problem​:

  my $server = IO​::Socket​::Async.listen('localhost', 3333);
  $server.tap​: -> $conn {
  $conn.Supply.tap​: -> $message { say $message.perl }
  }
 
  my $client = IO​::Socket​::Async.connect('localhost', 3333).then​: {
  .result.write(Blob.new​: 144);
  }
 
  await $client, $server;

It prints the following, and exits​:

  Unhandled exception​: Malformed UTF-8

In practice, having a server than can be crashed at will by any (even not-authenticated) client is of course LTA.
It seem the only way to prevent this, is to use .Supply(​:bin) to work with Buf's, which is needlessly cumbersome for text-based protocols.

I tried to catch the exception in the following ways, to prevent it from exiting the program, but none had an effect​:

1) CATCH or try/CATCH in a bunch of different places
2) Assigning to $*SCHEDULER.uncaught_handler
3) Specifying a :quit handler for both .tap's

From @jnthn

On Sat Aug 06 11​:25​:38 2016, smls75@​gmail.com wrote​:

Golfed program to demonstrate the problem​:

my $server = IO​::Socket​::Async.listen('localhost', 3333);
$server.tap​: -> $conn {
$conn.Supply.tap​: -> $message { say $message.perl }
}

my $client = IO​::Socket​::Async.connect('localhost', 3333).then​: {
.result.write(Blob.new​: 144);
}

await $client, $server;

It prints the following, and exits​:

Unhandled exception​: Malformed UTF-8

In practice, having a server than can be crashed at will by any (even
not-authenticated) client is of course LTA.
It seem the only way to prevent this, is to use .Supply(​:bin) to work
with Buf's, which is needlessly cumbersome for text-based protocols.

I tried to catch the exception in the following ways, to prevent it
from exiting the program, but none had an effect​:

1) CATCH or try/CATCH in a bunch of different places
2) Assigning to $*SCHEDULER.uncaught_handler
3) Specifying a :quit handler for both .tap's

Fixed, and test added in S32-io/IO-Socket-Async.t for this and a couple of other related cases. (Under the hood, the whole way we handle decoding strings with async sockets has been given a good overhaul.)

The typical way to handle such errors would be your option 3 (or, if using the supply/whenever syntax, a QUIT phaser). It should now also, as a last gasp, be passed to option 2.

/jnthn

The RT System itself - Status changed from 'new' to 'open'

@jnthn - Status changed from 'open' to 'resolved'