# How to get more info on w ∈ workers()

**URL:** <https://discourse.julialang.org/t/how-to-get-more-info-on-w-workers/34290>\
**Category:** Julia at Scale\
**Created:** [February 7, 2020, 9:53am UTC](https://discourse.julialang.org/t/how-to-get-more-info-on-w-workers/34290 "2020-02-07T09:53:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![healyp](https://avatars.discourse-cdn.com/v4/letter/h/67e7ee/32.png) [@healyp](https://discourse.julialang.org/u/healyp)\
**Post date:** [February 7, 2020, 9:53am UTC](https://discourse.julialang.org/t/how-to-get-more-info-on-w-workers/34290/1 "2020-02-07T09:53:22Z")

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I’m getting the following error

```julia
From worker 30:	ErrorException("Process(30) - Invalid connection credentials sent by remote.")CapturedException(ErrorException("Process(30) - Invalid connection credentials sent by remote."), Any[(error(::String) at error.jl:33, 1), (process_hdr(::Sockets.TCPSocket, ::Bool) at process_messages.jl:273, 1), (message_handler_loop(::Sockets.TCPSocket, ::Sockets.TCPSocket, ::Bool) at process_messages.jl:167, 1), (process_tcp_streams(::Sockets.TCPSocket, ::Sockets.TCPSocket, ::Bool) at process_messages.jl:142, 1), ((::Distributed.var"#101#102"{Sockets.TCPSocket,Sockets.TCPSocket,Bool})() at task.jl:333, 1)])
      From worker 30:	Process(30) - Unknown remote, closing connection.

```

This is a little strange in the first place for me since it is the only failure and I am using `addprocs()` to add 2 processes per machine on several machines that I assume to be identically configured (linux cluster in a student lab).

I have two questions:

1. What error should I be catching so that I can simply proceed without this worker?
2. For debugging purposes (and for general logging) I would like more information on worker 30. How can I know the hostname corresponding to this worker?

Many thanks.

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<div class="post-metadata">

**Author:** ![jemiryguo](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jemiryguo/32/18633_2.png) [@jemiryguo](https://discourse.julialang.org/u/jemiryguo)\
**Post date:** [October 1, 2020, 9:20am UTC](https://discourse.julialang.org/t/how-to-get-more-info-on-w-workers/34290/2 "2020-10-01T09:20:39Z")

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1 i’m not sure about that but seems `RemoteException` type is for this purpose, maybe you can refer to julia manual here [Distributed Computing · The Julia Language](https://docs.julialang.org/en/v1/stdlib/Distributed/#Distributed.RemoteException)

2 you can use `Distributed.map_pid_wrkr` function to map the pid to a `Worker` type, then you can lookup the hostname, such as `Distributed.map_pid_wrkr[pid].config.host`. `config` field is a `WorkConfig` type, and all field name can be obtained by `using Distrbuted; fieldnames(WorkerConfig)`, that is `(:io, :host, :port, :count, :exename, :exeflags, :userdata, :tunnel, :multiplex, :forward, :bind_addr, :sshflags, :max_parallel, :connect_at, :process, :ospid, :environ, :ident, :connect_idents, :enable_threaded_blas)`.