Re: Many "Bad file descriptor"s and Socket's break my communication

[David Daney <ddaney at avtrex dot com>]

Martin Egholm Nielsen wrote:
> Hi there,
>
> I've been using the last four days to narrow in a strange problem in my 
> webserver.
> I have a multi-threaded webserver running on an embedded ppc405 module 
> running Linux (2.4.2x) and libgcj (3.4.3 - ancient I know). The 
> webserver is running SSL (thanks to Jessie) with keep-alive support. Fine!
>
> However, due to a typo in my connecting SSL-client, I somehow forced the 
> client/server to create a new socket connection (and thereby start 
> SSL-handshaking) each time the client wanted to talk to the server.
> (The "somehow" on the client, was registering a new HostnameVerifier and 
> a new SSLSocketFactory on HttpsURLConnection.)
>
> This consequently made each thread belonging to an old request hang in a 
> "read()" way down in Jessie on a 
> gnu.java.net.PlainSocketImpl$SocketInputStream.
>
> However, as the sockets were "closed" (or whatever Sun's 
> HttpsURLConnection implementation does when "abandoning" its cached 
> sockets in my client) I would have expected the stuck invocations to 
> "read()" to return -1 more or less immediately afterwards. (As all the 
> faulty examples I've created to reproduce this does!)
> But no, instead of returning, they just keep being stuck there - but not 
> forever!
>
> After some 10-20 new connections to my server, _suddenly_ 10-20 stuck 
> read()'s "return" by throwing me IOException's with "Bad file descriptor"!
> And now, I really don't care if I get "-1" returned cleanly or I am 
> thrown these IOException - that is, _if_ it didn't "brake" the new 
> socket connection triggering the throwing.
> And for "brake" I have only a vague explanation:
>
> 1) Mostly I've seen "huge" amounts of data (~200 chars) disappear from 
> the triggering socket's inputstream. Resulting in my request-thread 
> getting stuck in a read() never getting any of the expected data.
> 2) On seldom occasions I've seen only "small" amount of characters 
> disappear - one char, and sometimes more.
>
> That was a long story, but I have a smole hope that somebody can guide 
> me further in solving this.
> Alternatively, I would really like to know how to provoke read() to 
> throw "Bad file descriptor" instead of -1, so that I might have a chance 
> reproducing this with a much smaller example.
It is hard to say exactly what is happening.  However it it possible 
that it is caused by the bug fixed by this:

http://gcc.gnu.org/ml/java-patches/2005-q1/msg00753.html

patch. It could of course be unrelated to that bug, in which case I can 
only wish you luck.

David Daney