[ovs-dev] [PATCH 2/4] ovsdb-idl.c: Allows retry even when using a single remote.

aginwala aginwala at asu.edu
Wed Aug 14 02:13:15 UTC 2019


On Tue, Aug 13, 2019 at 7:07 PM aginwala <aginwala at asu.edu> wrote:

> Thanks for the fixes. Found a bug in current code which breaks both nbctl
> with local socket and daemon mode on follower nodes. Also nbctl daemon mode
> always tries to connect to leader node by default which also failed to
> connect.
> e.g. export OVN_NB_DB=tcp:<lb_vip>:6641; ovn-nbctl  --pidfile --detach.
>  2019-08-14T01:07:06Z|00036|ovsdb_idl|INFO|unix:/var/run/openvswitch/ovnnb_db.sock:
> clustered database server is not cluster leader; trying another server
> 2019-08-14T01:07:06Z|00037|reconnect|DBG|unix:/var/run/openvswitch/ovnnb_db.sock:
> entering RECONNECT
> 2019-08-14T01:07:06Z|00038|ovsdb_idl|DBG|unix:/var/run/openvswitch/ovnnb_db.sock:
> SERVER_MONITOR_COND_REQUESTED -> RETRY at lib/ovsdb-idl.c:1917
> 2019-08-14T01:07:06Z|00039|poll_loop|DBG|wakeup due to 0-ms timeout at
> lib/reconnect.c:643
> 2019-08-14T01:07:06Z|00040|reconnect|INFO|unix:/var/run/openvswitch/ovnnb_db.sock:
> connection attempt timed out
> 2019-08-14T01:07:06Z|00041|reconnect|INFO|unix:/var/run/openvswitch/ovnnb_db.sock:
> waiting 2 seconds before reconnect
> 2019-08-14T01:07:06Z|00042|reconnect|DBG|unix:/var/run/openvswitch/ovnnb_db.sock:
> entering BACKOFF
>
> Need to explicitly specify no-leader-only to work around.  ovn-nbctl
> --pidfile --detach --no-leader-only.
> For LB VIP, since LB sees all nodes are active, connections are
> established to all cluster nodes equally. I am using round robin setting
> for LB VIP for 3 node cluster using raft.
>
> Hence, are we always going to avoid this behavior because this is forcing
> to always connect to leader and not to followers? So if we use this
> approach, idl will show ovn-nbctl: tcp:<lb_vip>:6641: database connection
> failed () if requests reaches followers and only processes success if
> request reaches leader node with this patch.
>
>
> On Tue, Aug 13, 2019 at 9:23 AM Han Zhou <zhouhan at gmail.com> wrote:
>
>> From: Han Zhou <hzhou8 at ebay.com>
>>
>> When clustered mode is used, the client needs to retry connecting
>> to new servers when certain failures happen. Today it is allowed to
>> retry new connection only if multiple remotes are used, which prevents
>> using LB VIP with clustered nodes. This patch makes sure the retry
>> logic works when using LB VIP: although same IP is used for retrying,
>> the LB can actually redirect the connection to a new node.
>>
>> Signed-off-by: Han Zhou <hzhou8 at ebay.com>
>> ---
>>  lib/ovsdb-idl.c        | 11 +++-------
>>  tests/ovsdb-cluster.at | 57
>> ++++++++++++++++++++++++++++++++++++++++++++++++++
>>  tests/test-ovsdb.c     |  1 +
>>  3 files changed, 61 insertions(+), 8 deletions(-)
>>
>> diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c
>> index 1a6a4af..190143f 100644
>> --- a/lib/ovsdb-idl.c
>> +++ b/lib/ovsdb-idl.c
>> @@ -657,12 +657,8 @@ ovsdb_idl_state_to_string(enum ovsdb_idl_state state)
>>  static void
>>  ovsdb_idl_retry_at(struct ovsdb_idl *idl, const char *where)
>>  {
>> -    if (idl->session && jsonrpc_session_get_n_remotes(idl->session) > 1)
>> {
>> -        ovsdb_idl_force_reconnect(idl);
>> -        ovsdb_idl_transition_at(idl, IDL_S_RETRY, where);
>> -    } else {
>> -        ovsdb_idl_transition_at(idl, IDL_S_ERROR, where);
>> -    }
>> +    ovsdb_idl_force_reconnect(idl);
>> +    ovsdb_idl_transition_at(idl, IDL_S_RETRY, where);
>>  }
>>
>>  static void
>> @@ -1895,8 +1891,7 @@ ovsdb_idl_check_server_db(struct ovsdb_idl *idl)
>>      if (!database) {
>>          VLOG_INFO_RL(&rl, "%s: server does not have %s database",
>>                       server_name, idl->data.class_->database);
>> -    } else if (!strcmp(database->model, "clustered")
>> -               && jsonrpc_session_get_n_remotes(idl->session) > 1) {
>> +    } else if (!strcmp(database->model, "clustered")) {
>>
> > I think this check jsonrpc_session_get_n_remotes(idl->session) > 1 is
> still needed for follower nodes for monitor condition to avoid this bug.
> Correct me if I am wrong or missed any case.
>
>          uint64_t index = database->n_index ? *database->index : 0;
>>
>>          if (!database->schema) {
>> diff --git a/tests/ovsdb-cluster.at b/tests/ovsdb-cluster.at
>> index 4701272..6a13843 100644
>> --- a/tests/ovsdb-cluster.at
>> +++ b/tests/ovsdb-cluster.at
>> @@ -63,6 +63,63 @@ m4_define([OVSDB_CHECK_EXECUTION],
>>  EXECUTION_EXAMPLES
>>
>>
>> +AT_BANNER([OVSDB - disconnect from cluster])
>> +
>> +# When a node is disconnected from the cluster, the IDL should disconnect
>> +# and retry even if it uses a single remote, because the remote IP can be
>> +# a VIP on a load-balance.
>> +AT_SETUP([OVSDB cluster - disconnect from cluster, single remote])
>> +AT_KEYWORDS([ovsdb server negative unix cluster disconnect])
>> +
>> +schema_name=`ovsdb-tool schema-name $abs_srcdir/idltest.ovsschema`
>> +ordinal_schema > schema
>> +AT_CHECK([ovsdb-tool '-vPATTERN:console:%c|%p|%m' create-cluster s1.db
>> $abs_srcdir/idltest.ovsschema unix:s1.raft], [0], [], [stderr])
>> +cid=`ovsdb-tool db-cid s1.db`
>> +schema_name=`ovsdb-tool schema-name $abs_srcdir/idltest.ovsschema`
>> +for i in `seq 2 3`; do
>> +    AT_CHECK([ovsdb-tool join-cluster s$i.db $schema_name unix:s$i.raft
>> unix:s1.raft])
>> +done
>> +
>> +on_exit 'kill `cat *.pid`'
>> +for i in `seq 3`; do
>> +    AT_CHECK([ovsdb-server -v -vconsole:off -vsyslog:off --detach
>> --no-chdir --log-file=s$i.log --pidfile=s$i.pid --unixctl=s$i
>> --remote=punix:s$i.ovsdb s$i.db])
>> +done
>> +for i in `seq 3`; do
>> +    AT_CHECK([ovsdb_client_wait unix:s$i.ovsdb $schema_name connected])
>> +done
>> +
>> +AT_CHECK([ovsdb-client transact unix:s1.ovsdb '[["idltest",
>> +      {"op": "insert",
>> +       "table": "simple",
>> +       "row": {"i": 1}}]]'], [0], [ignore], [ignore])
>> +
>> +# Connect to a single remote s3.  Use "wait" to trigger a non-op
>> transaction so
>> +# that test-ovsdb will not quit.
>> +
>> +on_exit 'pkill test-ovsdb'
>> +test-ovsdb '-vPATTERN:console:test-ovsdb|%c|%m' -v -t10 idl
>> unix:s3.ovsdb '[["idltest",
>> +      {"op": "wait",
>> +       "table": "simple",
>> +       "where": [["i", "==", 1]],
>> +       "columns": ["i"],
>> +       "until": "==",
>> +       "rows": [{"i": 1}]}]]' > test-ovsdb.log 2>&1 &
>> +
>> +OVS_WAIT_UNTIL([grep "000: i=1" test-ovsdb.log])
>> +
>> +# Shutdown the other 2 servers so that s3 is disconnected from the
>> cluster.
>> +for i in 2 1; do
>> +    OVS_APP_EXIT_AND_WAIT_BY_TARGET([`pwd`/s$i], [s$i.pid])
>> +done
>> +
>> +# The test-ovsdb should detect the disconnect and retry.
>> +OVS_WAIT_UNTIL([grep disconnect test-ovsdb.log])
>> +
>> +OVS_APP_EXIT_AND_WAIT_BY_TARGET([`pwd`/s3], [s3.pid])
>> +
>> +AT_CLEANUP
>> +
>> +
>>  OVS_START_SHELL_HELPERS
>>  # ovsdb_cluster_failure_test SCHEMA_FUNC OUTPUT TRANSACTION...
>>  ovsdb_cluster_failure_test () {
>> diff --git a/tests/test-ovsdb.c b/tests/test-ovsdb.c
>> index 187eb28..b1a4be3 100644
>> --- a/tests/test-ovsdb.c
>> +++ b/tests/test-ovsdb.c
>> @@ -2412,6 +2412,7 @@ do_idl(struct ovs_cmdl_context *ctx)
>>      track = ((struct test_ovsdb_pvt_context *)(ctx->pvt))->track;
>>
>>      idl = ovsdb_idl_create(ctx->argv[1], &idltest_idl_class, true, true);
>> +    ovsdb_idl_set_leader_only(idl, false);
>>      if (ctx->argc > 2) {
>>          struct stream *stream;
>>
>> --
>> 2.1.0
>>
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>>
>


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