dotnet-httprepl prints usage very slowly, repeats characters in Linux

[jdmallen]

Environment

dotnet --info Output:

.NET Core SDK (reflecting any global.json):
 Version:   2.2.100-preview2-009404
 Commit:    f4707d384d

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  18.04
 OS Platform: Linux
 RID:         ubuntu.18.04-x64
 Base Path:   /home/jesse/dotnet/sdk/2.2.100-preview2-009404/

Host (useful for support):
  Version: 2.2.0-preview2-26905-02
  Commit:  ad4d306fe0

.NET Core SDKs installed:
  2.2.100-preview2-009404 [/home/jesse/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.2.0-preview2-35157 [/home/jesse/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.2.0-preview2-35157 [/home/jesse/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.2.0-preview2-26905-02 [/home/jesse/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

Note: dotnet points to preview version on my machine.

Slow terminal printing

1. I installed latest dotnet-httprepl with this command:
   dotnet tool install -g dotnet-httprepl --version 2.2.0-preview3-35246 --add-source https://dotnet.myget.org/F/dotnet-core/api/v3/index.json

2. I created and ran a default webapi project: dotnet new webapi && dotnet run

3. I spun up dotnet-httprepl with dotnet-httprepl --help

The usage printed to the screen one line at a time extremely slowly. I timed it and it takes a full 10 seconds to print to the terminal.

Duplicated characters

The second issue is when I open a repl session, typing results in duplicate characters to be printed to the screen:

1. Run httprepl with dotnet-httprepl http://localhost:5000

jesse@xubuntu:~/git $ dotnet-httprepl http://localhost:5000
(Disconnected)~ set base "http://localhost:5000"

http://localhost:5000/~ lls

http://localhost:5000/~ II  am ttypiing a senttencce

No matching command found
Execute 'help' to se available commands

http://localhost:5000/~ II  aam  ccarefully ttypingg  tthis..  Myy  kkeyboard is not brokenn.e

No matching command found
Execute 'help' to se available commands

http://localhost:5000/~ sset  bbaase  hhttttppss::////lloocalhost::550001

https://localhost:5001/~

As you can see, it still understands the commands that are being typed, so I think it's just a display issue.

Also that string "Execute 'help' to se available commands" was copied verbatim from the output.

I'm looking forward to using this tool in my development! :)

[bradygaster]

@glennc just a note here - @mlorbetske confirmed this issue isn't resident in anything other than 18.04 and that tests validated this. That said, 18.04 is going to become the LTS for Ubuntu so this is still a thing.

[tomchavakis]

The same behavior occurred at Kubuntu 18.04 at 2.2.0-preview3-35497 version.

[mlorbetske]

I started looking at this yesterday, it seems we need analogous tweaks to the stty settings for the REPL session like we do for mac. The slow printing seems to be coming from repeatedly accessing CursorTop and CursorLeft in MoveCaret causing it to run in to this issue. I'll be testing some changes that reduce the number of accesses significantly soon.

[mlorbetske]

The duplicated characters has been fixed in #507, however the slow printing is still happening

[bradygaster]

Thanks for the update @mlorbetske - keep us posted and if we need to sync up or you uncover anything about which you're concerned during the fix ping us. cc @glennc

[vijayrkn]

Blocked on https://github.com/dotnet/corefx/issues/31517