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Make cluster meet reliable under link failures (valkey-io#461)
When there is a link failure while an ongoing MEET request is sent the sending node stops sending anymore MEET and starts sending PINGs. Since every node responds to PINGs from unknown nodes with a PONG, the receiving node never adds the sending node. But the sending node adds the receiving node when it sees a PONG. This can lead to asymmetry in cluster membership. This changes makes the sender keep sending MEET until it sees a PONG, avoiding the asymmetry. --------- Signed-off-by: Sankar <[email protected]> Signed-off-by: Ping Xie <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| # make sure the test infra won't use SELECT | ||
| set old_singledb $::singledb | ||
| set ::singledb 1 | ||
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| tags {tls:skip external:skip cluster} { | ||
| set base_conf [list cluster-enabled yes] | ||
| start_multiple_servers 2 [list overrides $base_conf] { | ||
| test "Cluster nodes are reachable" { | ||
| for {set id 0} {$id < [llength $::servers]} {incr id} { | ||
| # Every node should be reachable. | ||
| wait_for_condition 1000 50 { | ||
| ([catch {R $id ping} ping_reply] == 0) && | ||
| ($ping_reply eq {PONG}) | ||
| } else { | ||
| catch {R $id ping} err | ||
| fail "Node #$id keeps replying '$err' to PING." | ||
| } | ||
| } | ||
| } | ||
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| test "Before slots allocation, all nodes report cluster failure" { | ||
| wait_for_cluster_state fail | ||
| } | ||
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| set CLUSTER_PACKET_TYPE_PONG 1 | ||
| set CLUSTER_PACKET_TYPE_NONE -1 | ||
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| test "Cluster nodes haven't met each other" { | ||
| assert {[llength [get_cluster_nodes 1]] == 1} | ||
| assert {[llength [get_cluster_nodes 0]] == 1} | ||
| } | ||
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| test "Allocate slots" { | ||
| cluster_allocate_slots 2 0;# primaries replicas | ||
| } | ||
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| test "Multiple MEETs from Node 1 to Node 0 should work" { | ||
| # Make 1 drop the PONG responses to MEET | ||
| R 1 DEBUG DROP-CLUSTER-PACKET-FILTER $CLUSTER_PACKET_TYPE_PONG | ||
| # It is important to close the connection on drop, otherwise a subsequent MEET won't be sent | ||
| R 1 DEBUG CLOSE-CLUSTER-LINK-ON-PACKET-DROP 1 | ||
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| R 1 CLUSTER MEET 127.0.0.1 [srv 0 port] | ||
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| # Wait for at least a few MEETs to be sent so that we are sure that 1 is dropping the response to MEET. | ||
| wait_for_condition 1000 50 { | ||
| [CI 0 cluster_stats_messages_meet_received] > 1 && | ||
| [CI 1 cluster_state] eq {fail} && [CI 0 cluster_state] eq {ok} | ||
| } else { | ||
| fail "Cluster node 1 never sent multiple MEETs to 0" | ||
| } | ||
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| # 0 will be connected to 1, but 1 won't see that 0 is connected | ||
| assert {[llength [get_cluster_nodes 1 connected]] == 1} | ||
| assert {[llength [get_cluster_nodes 0 connected]] == 2} | ||
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| # Drop incoming and outgoing links from/to 1 | ||
| R 0 DEBUG CLUSTERLINK KILL ALL [R 1 CLUSTER MYID] | ||
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| # Wait for 0 to know about 1 again after 1 sends a MEET | ||
| wait_for_condition 1000 50 { | ||
| [llength [get_cluster_nodes 0 connected]] == 2 | ||
| } else { | ||
| fail "Cluster node 1 never sent multiple MEETs to 0" | ||
| } | ||
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| # Undo packet drop | ||
| R 1 DEBUG DROP-CLUSTER-PACKET-FILTER $CLUSTER_PACKET_TYPE_NONE | ||
| R 1 DEBUG CLOSE-CLUSTER-LINK-ON-PACKET-DROP 0 | ||
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| # Both a and b will turn to cluster state ok | ||
| wait_for_condition 1000 50 { | ||
| [CI 1 cluster_state] eq {ok} && [CI 0 cluster_state] eq {ok} && | ||
| [CI 1 cluster_stats_messages_meet_sent] == [CI 0 cluster_stats_messages_meet_received] | ||
| } else { | ||
| fail "1 cluster_state:[CI 1 cluster_state], 0 cluster_state: [CI 0 cluster_state]" | ||
| } | ||
| } | ||
| } ;# stop servers | ||
| } ;# tags | ||
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||
| set ::singledb $old_singledb | ||
|
|
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,71 @@ | ||
| # make sure the test infra won't use SELECT | ||
| set old_singledb $::singledb | ||
| set ::singledb 1 | ||
|
|
||
| tags {tls:skip external:skip cluster} { | ||
| set base_conf [list cluster-enabled yes] | ||
| start_multiple_servers 2 [list overrides $base_conf] { | ||
| test "Cluster nodes are reachable" { | ||
| for {set id 0} {$id < [llength $::servers]} {incr id} { | ||
| # Every node should be reachable. | ||
| wait_for_condition 1000 50 { | ||
| ([catch {R $id ping} ping_reply] == 0) && | ||
| ($ping_reply eq {PONG}) | ||
| } else { | ||
| catch {R $id ping} err | ||
| fail "Node #$id keeps replying '$err' to PING." | ||
| } | ||
| } | ||
| } | ||
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||
| test "Before slots allocation, all nodes report cluster failure" { | ||
| wait_for_cluster_state fail | ||
| } | ||
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| set CLUSTER_PACKET_TYPE_MEET 2 | ||
| set CLUSTER_PACKET_TYPE_NONE -1 | ||
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| test "Cluster nodes haven't met each other" { | ||
| assert {[llength [get_cluster_nodes 1]] == 1} | ||
| assert {[llength [get_cluster_nodes 0]] == 1} | ||
| } | ||
|
|
||
| test "Allocate slots" { | ||
| cluster_allocate_slots 2 0 | ||
| } | ||
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| test "MEET is reliable when target drops the initial MEETs" { | ||
| # Make 0 drop the initial MEET messages due to link failure | ||
| R 0 DEBUG DROP-CLUSTER-PACKET-FILTER $CLUSTER_PACKET_TYPE_MEET | ||
| R 0 DEBUG CLOSE-CLUSTER-LINK-ON-PACKET-DROP 1 | ||
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| R 1 CLUSTER MEET 127.0.0.1 [srv 0 port] | ||
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| # Wait for at least a few MEETs to be sent so that we are sure that 0 is | ||
| # dropping them. | ||
| wait_for_condition 1000 50 { | ||
| [CI 0 cluster_stats_messages_meet_received] >= 3 | ||
| } else { | ||
| fail "Cluster node 1 never sent multiple MEETs to 0" | ||
| } | ||
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| # Make sure the nodes still don't know about each other | ||
| assert {[llength [get_cluster_nodes 1 connected]] == 1} | ||
| assert {[llength [get_cluster_nodes 0 connected]] == 1} | ||
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| R 0 DEBUG DROP-CLUSTER-PACKET-FILTER $CLUSTER_PACKET_TYPE_NONE | ||
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| # If the MEET is reliable, both a and b will turn to cluster state ok | ||
| wait_for_condition 1000 50 { | ||
| [CI 1 cluster_state] eq {ok} && [CI 0 cluster_state] eq {ok} && | ||
| [CI 0 cluster_stats_messages_meet_received] >= 4 && | ||
| [CI 1 cluster_stats_messages_meet_sent] == [CI 0 cluster_stats_messages_meet_received] | ||
| } else { | ||
| fail "1 cluster_state:[CI 1 cluster_state], 0 cluster_state: [CI 0 cluster_state]" | ||
| } | ||
| } | ||
| } ;# stop servers | ||
| } ;# tags | ||
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| set ::singledb $old_singledb | ||
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