[jira] [Commented] (ARROW-822) [Python] StreamWriter fails to open with socket as sink

["Bryan Cutler (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-822?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15969255#comment-15969255 ] 

Bryan Cutler commented on ARROW-822:
------------------------------------

Some code to reproduce, if needed

{noformat}
    import pyarrow as pa
    import socket, os, io

    port = 8080

    for res in socket.getaddrinfo("localhost", port, socket.AF_UNSPEC, socket.SOCK_STREAM):
        af, socktype, proto, canonname, sa = res
        sock = socket.socket(af, socktype, proto)
        try:
            sock.settimeout(3)
            sock.connect(sa)
        except socket.error:
            sock.close()
            sock = None
            continue
        break
    if not sock:
        raise Exception("could not open socket")
    
    #sink = socket
    sink = sock.makefile("wb", 65536)
    #sink = os.fdopen(sock.fileno(), "wb", 65536)
    #sink = os.fdopen(os.dup(sock.fileno()), "wb", 65536)

    field = pa.Field.from_py("f1", pa.float32())
    schema = pa.Schema.from_fields([field])

    writer = pa.StreamWriter(sink, schema)
{noformat}

> [Python] StreamWriter fails to open with socket as sink
> -------------------------------------------------------
>
>                 Key: ARROW-822
>                 URL: https://issues.apache.org/jira/browse/ARROW-822
>             Project: Apache Arrow
>          Issue Type: Bug
>            Reporter: Bryan Cutler
>
> Trying to use pyarrow StreamWriter to write to a socket fails.  I've tried the following:
> - Use socket directly and get "TypeError: Unable to read from object of type: <class 'socket._socketobject'>"
>   looks like pyarrow expects the object to have a "write" attribute
> - Using as a file object with: "sock.makefile("wb", 65536)" get the error "pyarrow.error.ArrowIOError: IOError: '_fileobject' object has no attribute 'tell'"
>   Not sure why exactly "tell" is required.
> - using "os.fdopen(sock.fileno(), "wb", 65536)" get a rather cryptic error that I've been unable to track down:
>   "terminate called after throwing an instance of 'std::logic_error' what():  basic_string::_M_construct null not valid"
>   Seems to indicate some kind of std::string construction with a NULL, but I can't find that anywhere



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