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https://issues.apache.org/jira/browse/ZOOKEEPER-3698?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17019297#comment-17019297
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Mate Szalay-Beko edited comment on ZOOKEEPER-3698 at 1/20/20 8:35 AM:
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I can agree with 3) and 4).
Regarding 3) I will add to the documentation, that disabling the reachability
check will cause the cluster not to be able to reconfigure itself properly
during network problems, so the disabling is useful only during testing. For
the same reason I would keep it enabled by default.
Also I don't think 1), the parallel stream would be an issue here.
Regarding 2) I think it won't hurt, but won't really help either. I tested it
by raising the hardcoded timeout value up to 5 sec, and it didn't solve the
problem. (My hypothesis is that the ICMP calls might fail quickly on mac, not
waiting / retrying during the timeout period.) Still, being able to fine-tune
this parameter might be a good idea on production environment. I also agree
with the slightly higher default value of 1 sec. Exactly because of the
parallel stream, we should get back the address from the list with the quickest
ping time.
was (Author: symat):
I can agree with 3) and 4).
Regarding 3) I will add to the documentation, that disabling the reachability
check will cause the cluster not to be able to reconfigure itself properly
during network problems, so the disabling is useful only during testing.
Also I don't think 1), the parallel stream would be an issue here.
Regarding 2) I think it won't hurt, but won't really help either. I tested it
by raising the hardcoded timeout value up to 5 sec, and it didn't solve the
problem. (My hypothesis is that the ICMP calls might fail quickly on mac, not
waiting / retrying during the timeout period.) Still, being able to fine-tune
this parameter might be a good idea on production environment. I also agree
with the slightly higher default value of 1 sec. Exactly because of the
parallel stream, we should get back the address from the list with the quickest
ping time.
> NoRouteToHostException when starting large ZooKeeper cluster on localhost
> -------------------------------------------------------------------------
>
> Key: ZOOKEEPER-3698
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3698
> Project: ZooKeeper
> Issue Type: Bug
> Reporter: Mate Szalay-Beko
> Assignee: Mate Szalay-Beko
> Priority: Major
> Fix For: 3.6.0
>
>
> During testing RC for 3.6.0, we found that ZooKeeper cluster with large
> number of ensemble members (e.g. 23) can not start properly. We see a lot of
> warnings in the log:
> {code:java}
> 2020-01-15 20:02:13,431 [myid:13] - WARN
> [ListenerHandler-phunt-MBP13.local/192.168.1.91:4193:QuorumCnxManager@691]
> - None of the addresses (/192.168.1.91:4190) are reachable for sid 10
> java.net.NoRouteToHostException: No valid address among [/192.168.1.91:4190]
> {code}
> and also:
> {code:java}
> 2020-01-17 11:02:26,177 [myid:4] - WARN
> [Thread-2531:QuorumCnxManager$SendWorker@1269] - destination address
> /127.0.0.1 not reachable anymore, shutting down the SendWorker for sid 6
> {code}
> The exceptions are happening when the new MultiAddress feature tries to
> filter the unreachable hosts from the address list. This involves the calling
> of the InetAddress.isReachable method with a default timeout of 500ms, which
> goes down to a native call in java and basically try to do a ping (an ICMP
> echo request) to the host. Naturally, the localhost should be always
> reachable. For some reason, this call gets failed (timeouted or simly
> refused) on mac if we have many ensemble members. I tested with 9 members and
> the cluster started properly. With 11-13-15 members it took more and more
> time to get the cluster to start, and the "NoRouteToHostException" started to
> appear in the logs. After around 1 minute the 15 ensemble members cluster
> started, but obviously this is not good this way. (I also tried with JDK 11
> but the I found the same behaviour)
>
> On linux, I haven't been able to reproduce the problem. I tried with 5, 9, 15
> and 23 ensemble members and the quorum always seems to start properly in a
> few seconds. (I used OpenJDK 1.8.232 on Ubuntu 18.04)
> *Update*:
> On mac, we we have the ICMP rate limit set to 250 by default. You can turn
> this off using the following command: sudo sysctl -w net.inet.icmp.icmplim=0
> (see [https://krypted.com/mac-os-x/disable-icmp-rate-limiting-os-x/])
> Using the above command before starting the 23 ensemble members cluster
> locally seems to solve the problem for me. (can someone verify?) The question
> is if this workaround is enough or not.
> As far as I can tell, the current code will generate {{2*A*(M-1)}} ICMP calls
> in each ZooKeeper server during startup, if {{'M'}} is the number of ensemble
> members and {{'A'}} is the number of election addresses provided for each
> member. This is not that high, if each ZooKeeper server is started on a
> different machine, but if we start a lot of ZooKeeper servers on a single
> machine, then it can quickly go beyond the predefined limit of 250 for mac.
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