[mod_cluster-issues] [JBoss JIRA] (MODCLUSTER-487) Default AdvertiseBindAddress value should not be NULL (UDP Multicast on Linux systems with more NICs)
Michal Karm Babacek (JIRA)
issues at jboss.org
Tue Mar 29 05:32:00 EDT 2016
[ https://issues.jboss.org/browse/MODCLUSTER-487?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michal Karm Babacek updated MODCLUSTER-487:
-------------------------------------------
Summary: Default AdvertiseBindAddress value should not be NULL (UDP Multicast on Linux systems with more NICs) (was: Advertise: UDP Multicast on Linux systems with more NICs: datagrams could be delayed or lost)
> Default AdvertiseBindAddress value should not be NULL (UDP Multicast on Linux systems with more NICs)
> -----------------------------------------------------------------------------------------------------
>
> Key: MODCLUSTER-487
> URL: https://issues.jboss.org/browse/MODCLUSTER-487
> Project: mod_cluster
> Issue Type: Bug
> Components: Native (httpd modules)
> Affects Versions: 1.2.11.Final, 1.3.1.Final
> Environment: Linux, multiple NICs environment
> Reporter: Michal Karm Babacek
> Assignee: Michal Karm Babacek
> Priority: Critical
> Attachments: advertise-linux3_x86_64.zip, advertise-windows_x86.zip, Advertize.class
>
>
> Credit where it's due: the issue was first spotted by [~rhatlapa].
> h3. Problem
> It appears that trying to send to all interfaces with {{NULL}} or {{"0.0.0.0"}} in the following statement actually picks the first non-loopback interface and sends to it.
> The result is that there is no datagram on other interfaces. Surprisingly, this is not deterministic though: After dozens or hundreds of messages, eventually one datagram reaches another interface.
> {code}
> if ((rv = apr_sockaddr_info_get(&ma_niface_sa, NULL,
> ma_mgroup_sa->family, 0,
> APR_UNSPEC, pool)) != APR_SUCCESS) {
> ap_log_error(APLOG_MARK, APLOG_ERR, rv, s,
> "mod_advertise: ma_group_join apr_sockaddr_info_get(0.0.0.0:0) failed");
> return rv;
> }
> {code}
> h3. Impact
> Picture this simple scenario: There are two interfaces, e.g.
> {noformat}
> enp1s0 10.16.88.187
> enp2s0 172.18.0.1
> {noformat}
> listed in this exact order with {{ip addr show}}.
> One has an EAP 7 (Wildfly 10) instance with mod_cluster bound to {{172.18.0.1}} IP address, which implies {{enp2s0}} interface.
> Furthermore, one has an Apache HTTP Server instance with mod_cluster bound to {{172.18.0.1}} IP address, i.e. MCMP VirtualHost and main VirtualHost all Listen on this IP address.
> Result: Without advertising, using an explicit {{proxy-list}}, all is well. MCMP works, requests work, balancing works.
> On the other hand, relying on advertisement, it could take EAP 7 (Wildfly 10) *minutes* to register with the balancer.
> The reason is that a vast majority of UDP Multicast datagrams arrives at enp1s0 and EAP 7 (Wildfly 10) doesn't see them.
> h3. Reproducer
> Lemme demonstrate with a recently refactored [advertise.c|https://github.com/Karm/mod_cluster/tree/advertise-native-test/test/native/advertise] utility for sending datagrams and the well known [Advertize.java|https://raw.githubusercontent.com/modcluster/mod_cluster/master/test/java/Advertize.java] utility for receiving them.
> Your your convenience, here are binaries built from the aforementioned sources:
> * Advertize java utility: [^Advertize.class]
> * advertise native utility (Linux3 x86_64): [^advertise-linux3_x86_64.zip]
> * advertise native utility (WIndows x86): [^advertise-windows_x86.zip]
> h3. Demonstration on Linux
> h4. System
> {noformat}
> [mbabacek at perf09 ~]$ ip addr show
> 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
> link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
> inet 127.0.0.1/8 scope host lo
> valid_lft forever preferred_lft forever
> 2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
> link/ether 00:18:8b:7a:46:04 brd ff:ff:ff:ff:ff:ff
> inet 10.16.88.187/21 brd 10.16.95.255 scope global enp1s0
> valid_lft forever preferred_lft forever
> inet 10.16.93.253/21 brd 10.16.95.255 scope global secondary enp1s0
> valid_lft forever preferred_lft forever
> 3: enp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
> link/ether 00:18:8b:7a:46:05 brd ff:ff:ff:ff:ff:ff
> inet 172.17.72.254/19 brd 172.17.95.255 scope global enp2s0
> valid_lft forever preferred_lft forever
> 4: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN
> link/ether 02:42:07:ab:74:f9 brd ff:ff:ff:ff:ff:ff
> inet 172.18.0.1/16 scope global docker0
> valid_lft forever preferred_lft forever
> {noformat}
> h4. Java
> {noformat}
> [mbabacek at perf09 ~]$ java -version
> openjdk version "1.8.0_71"
> OpenJDK Runtime Environment (build 1.8.0_71-b15)
> OpenJDK 64-Bit Server VM (build 25.71-b15, mixed mode)
> {noformat}
> h4.Advertise SENT
> {noformat}
> [mbabacek at perf09 ~]$ date;./advertise -a 224.0.1.102 -p 33364
> Mon Mar 21 12:39:51 EDT 2016
> UDP Multicast address to send datagrams to. Value: 224.0.1.102
> UDP Multicast port. Value: 33364
> IP address of the NIC to bound to. Value: NULL
> apr_socket_bind on 0.0.0.0:0
> apr_mcast_join on 0.0.0.0:0
> apr_socket_sendto to 224.0.1.102:33364
> {noformat}
> h4. Advertize RECEIVED
> YES (/)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364
> Linux like OS
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 16:39:51 GMT
> received from /10.16.88.187:38907
> {noformat}
> YES (/)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364 10.16.88.187
> Linux like OS
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 16:39:51 GMT
> received from /10.16.88.187:38907
> {noformat}
> NO (x)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364 172.17.72.254
> Linux like OS
> ready waiting...
> {noformat}
> YES (/)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364 0.0.0.0
> Linux like OS
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 16:39:51 GMT
> received from /10.16.88.187:38907
> {noformat}
> And now let's take a look at {{172.17.72.254}}, i.e. {{enp2s0}}
> h4. Advertise SENT
> {noformat}
> [mbabacek at perf09 ~]$ date;./advertise -a 224.0.1.102 -p 33364 -n 172.17.72.254
> Mon Mar 21 12:42:57 EDT 2016
> UDP Multicast address to send datagrams to. Value: 224.0.1.102
> UDP Multicast port. Value: 33364
> IP address of the NIC to bound to. Value: 172.17.72.254
> apr_socket_bind on 172.17.72.254:0
> apr_mcast_join on 172.17.72.254:0
> apr_socket_sendto to 224.0.1.102:33364
> {noformat}
> h4. Advertize RECEIVED
> NO (x)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364
> Linux like OS
> ready waiting...
> {noformat}
> NO (x)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364 10.16.88.187
> Linux like OS
> ready waiting...
> {noformat}
> YES (/)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364 172.17.72.254
> Linux like OS
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 16:42:57 GMT
> received from /172.17.72.254:35452
> {noformat}
> NO (x)
> {noformat}
> [mbabacek at perf09 ~]$ java Advertize 224.0.1.102 33364 0.0.0.0
> Linux like OS
> ready waiting...
> {noformat}
> h3. Demonstration on Windows
> One could note that the problem doesn't exist on Windows. All interfaces receive advertising.
> h4. Advertise SENT
> {noformat}
> C:\Users\karm\advertise-build
> λ advertise.exe -a 224.0.1.102 -p 33364
> UDP Multicast address to send datagrams to. Value: 224.0.1.102
> UDP Multicast port. Value: 33364
> IP address of the NIC to bound to. Value: NULL
> apr_socket_bind on 0.0.0.0:0
> apr_mcast_join on 0.0.0.0:0
> apr_socket_sendto to 224.0.1.102:33364
> {noformat}
> h4. Advertize RECEIVED
> YES (/)
> {noformat}
> C:\Users\karm\WORKSPACE
> λ "C:\Program Files\Java\jdk1.8.0_74\bin\java" Advertize 224.0.1.102 33364
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 18:07:50 GMT
> received from /192.168.122.52:61805
> {noformat}
> YES (/)
> {noformat}
> C:\Users\karm\WORKSPACE
> λ "C:\Program Files\Java\jdk1.8.0_74\bin\java" Advertize 224.0.1.102 33364 192.168.122.52
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 18:07:50 GMT
> received from /192.168.122.52:61805
> {noformat}
> YES (/)
> {noformat}
> C:\Users\karm\WORKSPACE
> λ "C:\Program Files\Java\jdk1.8.0_74\bin\java" Advertize 224.0.1.102 33364 192.168.122.199
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 18:07:50 GMT
> received from /192.168.122.52:61805
> {noformat}
> h4. Advertise SENT
> {noformat}
> C:\Users\karm\advertise-build
> λ advertise.exe -a 224.0.1.102 -p 33364 -n 192.168.122.199
> UDP Multicast address to send datagrams to. Value: 224.0.1.102
> UDP Multicast port. Value: 33364
> IP address of the NIC to bound to. Value: 192.168.122.199
> apr_socket_bind on 192.168.122.199:0
> apr_mcast_join on 192.168.122.199:0
> apr_socket_sendto to 224.0.1.102:33364
> {noformat}
> h4. Advertize RECEIVED
> YES (/)
> {noformat}
> C:\Users\karm\WORKSPACE
> λ "C:\Program Files\Java\jdk1.8.0_74\bin\java" Advertize 224.0.1.102 33364
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 18:09:55 GMT
> received from /192.168.122.199:52781
> {noformat}
> YES (/)
> {noformat}
> C:\Users\karm\WORKSPACE
> λ "C:\Program Files\Java\jdk1.8.0_74\bin\java" Advertize 224.0.1.102 33364 192.168.122.52
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 18:09:55 GMT
> received from /192.168.122.199:52781
> {noformat}
> YES (/)
> {noformat}
> C:\Users\karm\WORKSPACE
> λ "C:\Program Files\Java\jdk1.8.0_74\bin\java" Advertize 224.0.1.102 33364 192.168.122.199
> ready waiting...
> received: Advertize !!! Mon, 21 Mar 2016 18:09:55 GMT
> received from /192.168.122.199:52781
> {noformat}
> Ideas? :) [~jfclere], [~rhusar]
> I suggest adding {{bindaddr}} from AdvertiseBindAddress instead of NULL or perhaps adding a configuration directive that lets one to pick either MCMP VirtualHost ip address or default -- NULL.
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