Requests equi-distant from each other can create dead-lock loops
because the uid changes. Without disabling request coalescing
altogether I could not think of a better solution, but this solves 90%
of the problem.
There is another deadlock condition regarding probablisticHtl
decrementing which is much less likely (requires at least a 5-node
race condition) as follows:
B
A C
D
E
C, D, & E each respectively probabilistically don't decrement
(1) Node A (2/11) & B(2/22) both start/route a request (htl/uid)
(2) D routes to E (1/11)
(3) C routes to D (1/22), where the request is coalesced with (1/11)
(4) E routes to C where the request is coalesced with (1/22).
Without this patch even if it were only two nodes starting (for
example, a USK fetch) at the same time, they would each ask the other
and each request would be coalesced onto the other.
--
Robert Hailey
On Jan 18, 2008, at 11:02 PM, robert at freenetproject.org wrote:
> Author: robert
> Date: 2008-01-19 05:02:58 +0000 (Sat, 19 Jan 2008)
> New Revision: 17164
>
> Modified:
> trunk/freenet/src/freenet/node/Node.java
> trunk/freenet/src/freenet/node/RequestSender.java
> Log:
> fix fatal timeout
>
>
> Modified: trunk/freenet/src/freenet/node/Node.java
> ===================================================================
> --- trunk/freenet/src/freenet/node/Node.java 2008-01-19 03:33:18 UTC
> (rev 17163)
> +++ trunk/freenet/src/freenet/node/Node.java 2008-01-19 05:02:58 UTC
> (rev 17164)
> @@ -1779,7 +1779,7 @@
> // Request coalescing
> KeyHTLPair kh = new KeyHTLPair(key, htl);
> sender = (RequestSender) requestSenders.get(kh);
> - if(sender != null) {
> + if(sender != null && !sender.isLocalRequestSearch()) {
> if(logMINOR) Logger.minor(this, "Found sender:
> "+sender+" for
> "+uid);
> return sender;
> }
>
> Modified: trunk/freenet/src/freenet/node/RequestSender.java
> ===================================================================
> --- trunk/freenet/src/freenet/node/RequestSender.java 2008-01-19
> 03:33:18 UTC (rev 17163)
> +++ trunk/freenet/src/freenet/node/RequestSender.java 2008-01-19
> 05:02:58 UTC (rev 17164)
> @@ -851,4 +851,8 @@
> synchronized int getRecentlyFailedTimeLeft() {
> return recentlyFailedTimeLeft;
> }
> +
> + public boolean isLocalRequestSearch() {
> + return (source==null);
> + }
> }
>
> _______________________________________________
> cvs mailing list
> cvs at freenetproject.org
> http://emu.freenetproject.org/cgi-bin/mailman/listinfo/cvs
>
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