I applied these first three commits to master.
On Mon, Apr 01, 2013 at 10:17:15AM -0700, Justin Pettit wrote:
> Looks good.
>
> --Justin
>
>
> On Mar 27, 2013, at 2:44 PM, Ben Pfaff <b...@nicira.com> wrote:
>
> > Consider this situation:
> >
> > * OVSDB client A executes transactions very quickly for a long time.
> >
> > * OVSDB client B monitors the tables that A modifies, but (either
> > because B is connected over a slow network, or because B is slow to
> > process updates) cannot keep up.
> >
> > In this situation, the data that ovsdb-server has queued to send B grows
> > without bound and eventually ovsdb-server runs out of memory. This commit
> > avoids the problem by noticing that more data is queued to B than necessary
> > to express the whole contents of the database and dropping the connection
> > to B. When B reconnects later, it can then fetch the contents of the
> > database using less data than was previously queued to it.
> >
> > (This is not entirely hypothetical. We have seen this behavior in
> > intentional stress tests.)
> >
> > Bug #15637.
> > Reported-by: Jeff Merrick <jmerr...@vmware.com>
> > Signed-off-by: Ben Pfaff <b...@nicira.com>
> > ---
> > ovsdb/jsonrpc-server.c | 108
> > +++++++++++++++++++++++++++++++++++++++++++++++-
> > 1 files changed, 107 insertions(+), 1 deletions(-)
> >
> > diff --git a/ovsdb/jsonrpc-server.c b/ovsdb/jsonrpc-server.c
> > index 6e0a6f6..febc351 100644
> > --- a/ovsdb/jsonrpc-server.c
> > +++ b/ovsdb/jsonrpc-server.c
> > @@ -82,6 +82,8 @@ static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_cancel(
> > struct json_array *params,
> > const struct json *request_id);
> > static void ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session
> > *);
> > +static size_t ovsdb_jsonrpc_monitor_json_length_all(
> > + struct ovsdb_jsonrpc_session *);
> >
> > /* JSON-RPC database server. */
> >
> > @@ -335,6 +337,8 @@ struct ovsdb_jsonrpc_session {
> > struct list node; /* Element in remote's sessions list. */
> > struct ovsdb_session up;
> > struct ovsdb_jsonrpc_remote *remote;
> > + size_t backlog_threshold; /* See ovsdb_jsonrpc_session_run(). */
> > + size_t reply_backlog;
> >
> > /* Triggers. */
> > struct hmap triggers; /* Hmap of "struct ovsdb_jsonrpc_trigger"s.
> > */
> > @@ -371,6 +375,8 @@ ovsdb_jsonrpc_session_create(struct
> > ovsdb_jsonrpc_remote *remote,
> > list_push_back(&remote->sessions, &s->node);
> > hmap_init(&s->triggers);
> > hmap_init(&s->monitors);
> > + s->reply_backlog = 0;
> > + s->backlog_threshold = 1024 * 1024;
> > s->js = js;
> > s->js_seqno = jsonrpc_session_get_seqno(js);
> >
> > @@ -399,6 +405,8 @@ ovsdb_jsonrpc_session_close(struct
> > ovsdb_jsonrpc_session *s)
> > static int
> > ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
> > {
> > + size_t backlog;
> > +
> > jsonrpc_session_run(s->js);
> > if (s->js_seqno != jsonrpc_session_get_seqno(s->js)) {
> > s->js_seqno = jsonrpc_session_get_seqno(s->js);
> > @@ -409,7 +417,8 @@ ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session
> > *s)
> >
> > ovsdb_jsonrpc_trigger_complete_done(s);
> >
> > - if (!jsonrpc_session_get_backlog(s->js)) {
> > + backlog = jsonrpc_session_get_backlog(s->js);
> > + if (!backlog) {
> > struct jsonrpc_msg *msg = jsonrpc_session_recv(s->js);
> > if (msg) {
> > if (msg->type == JSONRPC_REQUEST) {
> > @@ -424,6 +433,39 @@ ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session
> > *s)
> > jsonrpc_msg_destroy(msg);
> > }
> > }
> > + s->reply_backlog = jsonrpc_session_get_backlog(s->js);
> > + } else if (backlog > s->reply_backlog + s->backlog_threshold) {
> > + /* We have a lot of data queued to send to the client. The data is
> > + * likely to be mostly monitor updates. It is unlikely that the
> > + * monitor updates are due to transactions by 's', because we will
> > not
> > + * let 's' make any more transactions until it drains its backlog
> > to 0
> > + * (see previous 'if' case). So the monitor updates are probably
> > due
> > + * to transactions made by database clients other than 's'. We
> > can't
> > + * fix that by preventing 's' from executing more transactions. We
> > + * could fix it by preventing every client from executing
> > transactions,
> > + * but then one slow or hung client could prevent other clients
> > from
> > + * doing useful work.
> > + *
> > + * Our solution is to cap the maximum backlog to O(1) in the
> > amount of
> > + * data in the database. If the backlog exceeds that amount, then
> > we
> > + * disconnect the client. When it reconnects, it can fetch the
> > entire
> > + * contents of the database using less data than was previously
> > + * backlogged. */
> > + size_t monitor_length;
> > +
> > + monitor_length = ovsdb_jsonrpc_monitor_json_length_all(s);
> > + if (backlog > s->reply_backlog + monitor_length * 2) {
> > + VLOG_INFO("%s: %zu bytes backlogged but a complete replica "
> > + "would only take %zu bytes, disconnecting",
> > + jsonrpc_session_get_name(s->js),
> > + backlog - s->reply_backlog, monitor_length);
> > + jsonrpc_session_force_reconnect(s->js);
> > + } else {
> > + /* The backlog is not unreasonably big. Only check again
> > after it
> > + * becomes much bigger. */
> > + s->backlog_threshold = 2 * MAX(s->backlog_threshold * 2,
> > + monitor_length);
> > + }
> > }
> > return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
> > }
> > @@ -1023,6 +1065,8 @@ struct ovsdb_jsonrpc_monitor
> > *ovsdb_jsonrpc_monitor_find(
> > static void ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *);
> > static struct json *ovsdb_jsonrpc_monitor_get_initial(
> > const struct ovsdb_jsonrpc_monitor *);
> > +static size_t ovsdb_jsonrpc_monitor_json_length(
> > + const struct ovsdb_jsonrpc_monitor *);
> >
> > static bool
> > parse_bool(struct ovsdb_parser *parser, const char *name, bool
> > default_value)
> > @@ -1292,6 +1336,22 @@ ovsdb_jsonrpc_monitor_remove_all(struct
> > ovsdb_jsonrpc_session *s)
> > }
> > }
> >
> > +/* Returns an overestimate of the number of bytes of JSON data required to
> > + * report the current contents of the database over all the monitors
> > currently
> > + * configured in 's'. */
> > +static size_t
> > +ovsdb_jsonrpc_monitor_json_length_all(struct ovsdb_jsonrpc_session *s)
> > +{
> > + struct ovsdb_jsonrpc_monitor *m;
> > + size_t length;
> > +
> > + length = 0;
> > + HMAP_FOR_EACH (m, node, &s->monitors) {
> > + length += ovsdb_jsonrpc_monitor_json_length(m);
> > + }
> > + return length;
> > +}
> > +
> > static struct ovsdb_jsonrpc_monitor *
> > ovsdb_jsonrpc_monitor_cast(struct ovsdb_replica *replica)
> > {
> > @@ -1427,6 +1487,52 @@ ovsdb_jsonrpc_monitor_change_cb(const struct
> > ovsdb_row *old,
> > return true;
> > }
> >
> > +/* Returns an overestimate of the number of bytes of JSON data required to
> > + * report the current contents of the database over monitor 'm'. */
> > +static size_t
> > +ovsdb_jsonrpc_monitor_json_length(const struct ovsdb_jsonrpc_monitor *m)
> > +{
> > + const struct shash_node *node;
> > + size_t length;
> > +
> > + /* Top-level overhead of monitor JSON. */
> > + length = 256;
> > +
> > + SHASH_FOR_EACH (node, &m->tables) {
> > + const struct ovsdb_jsonrpc_monitor_table *mt = node->data;
> > + const struct ovsdb_table *table = mt->table;
> > + const struct ovsdb_row *row;
> > + size_t i;
> > +
> > + /* Per-table JSON overhead: "<table>":{...}. */
> > + length += strlen(table->schema->name) + 32;
> > +
> > + /* Per-row JSON overhead: ,"<uuid>":{"old":{...},"new":{...}} */
> > + length += hmap_count(&table->rows) * (UUID_LEN + 32);
> > +
> > + /* Per-row, per-column JSON overhead: ,"<column>": */
> > + for (i = 0; i < mt->n_columns; i++) {
> > + const struct ovsdb_jsonrpc_monitor_column *c = &mt->columns[i];
> > + const struct ovsdb_column *column = c->column;
> > +
> > + length += hmap_count(&table->rows) * (8 +
> > strlen(column->name));
> > + }
> > +
> > + /* Data. */
> > + HMAP_FOR_EACH (row, hmap_node, &table->rows) {
> > + for (i = 0; i < mt->n_columns; i++) {
> > + const struct ovsdb_jsonrpc_monitor_column *c =
> > &mt->columns[i];
> > + const struct ovsdb_column *column = c->column;
> > +
> > + length +=
> > ovsdb_datum_json_length(&row->fields[column->index],
> > + &column->type);
> > + }
> > + }
> > + }
> > +
> > + return length;
> > +}
> > +
> > static void
> > ovsdb_jsonrpc_monitor_init_aux(struct ovsdb_jsonrpc_monitor_aux *aux,
> > const struct ovsdb_jsonrpc_monitor *m,
> > --
> > 1.7.2.5
> >
> > _______________________________________________
> > dev mailing list
> > dev@openvswitch.org
> > http://openvswitch.org/mailman/listinfo/dev
>
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