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Use max_statement_time

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Used only with supporting server versions. Using the time limit ensures that
the server interrupts the query at the same point Connector-C would cut the
connection. This prevents lingering queries.

Also, cleans up some associated error messages.
This commit is contained in:
Esa Korhonen
2018-11-20 18:47:29 +02:00
parent 0a5a3309e0
commit b47d4a4105
1 changed files with 29 additions and 11 deletions
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40
server/modules/monitor/mariadbmon/mariadbserver.cc
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@ -128,16 +128,16 @@ bool MariaDBServer::execute_cmd_ex(const string& cmd, QueryRetryMode mode,
{ {
int cols = mysql_num_fields(result); int cols = mysql_num_fields(result);
int rows = mysql_num_rows(result); int rows = mysql_num_rows(result);
*errmsg_out = string_printf("Query '%s' returned %d columns and %d rows of data when none " *errmsg_out = string_printf("Query '%s' on '%s' returned %d columns and %d rows of data when "
"was expected.", "none was expected.", cmd.c_str(), name(), cols, rows);
cmd.c_str(), cols, rows);
} }
} }
else else
{ {
if (errmsg_out) if (errmsg_out)
{ {
*errmsg_out = string_printf("Query '%s' failed: '%s'.", cmd.c_str(), mysql_error(conn)); *errmsg_out = string_printf("Query '%s' failed on '%s': '%s' (%i).",
cmd.c_str(), name(), mysql_error(conn), mysql_errno(conn));
} }
if (errno_out) if (errno_out)
{ {
@ -160,7 +160,8 @@ bool MariaDBServer::execute_cmd_no_retry(const std::string& cmd,
/** /**
* Execute a query which does not return data. If the query fails because of a network error * Execute a query which does not return data. If the query fails because of a network error
* (e.g. Connector-C timeout), automatically retry the query until time is up. * (e.g. Connector-C timeout), automatically retry the query until time is up. Uses max_statement_time
* when available to ensure no lingering timed out commands are left on the server.
* *
* @param cmd The query to execute. Should be a query with a predictable effect even when retried or * @param cmd The query to execute. Should be a query with a predictable effect even when retried or
* ran several times. * ran several times.
@ -173,6 +174,20 @@ bool MariaDBServer::execute_cmd_time_limit(const std::string& cmd, maxbase::Dura
std::string* errmsg_out) std::string* errmsg_out)
{ {
StopWatch timer; StopWatch timer;
string cmd_prefix;
int connector_timeout = -1;
if (m_capabilities.max_statement_time)
{
MXB_AT_DEBUG(int rv = ) mysql_get_optionv(m_server_base->con, MYSQL_OPT_READ_TIMEOUT,
&connector_timeout);
mxb_assert(rv == 0);
if (connector_timeout > 0)
{
cmd_prefix = string_printf("SET STATEMENT max_statement_time=%i FOR ", connector_timeout);
}
}
string command = cmd_prefix + cmd;
// If a query lasts less than 1s, sleep so that at most 1 query/s is sent. // If a query lasts less than 1s, sleep so that at most 1 query/s is sent.
// This prevents busy-looping when faced with some network errors. // This prevents busy-looping when faced with some network errors.
const Duration min_query_time(1.0); const Duration min_query_time(1.0);
@ -184,18 +199,22 @@ bool MariaDBServer::execute_cmd_time_limit(const std::string& cmd, maxbase::Dura
StopWatch query_timer; StopWatch query_timer;
string error_msg; string error_msg;
unsigned int errornum = 0; unsigned int errornum = 0;
cmd_success = execute_cmd_no_retry(cmd, &error_msg, &errornum); cmd_success = execute_cmd_no_retry(command, &error_msg, &errornum);
auto query_time = query_timer.lap(); auto query_time = query_timer.lap();
// Check if there is time to retry. // Check if there is time to retry.
Duration time_remaining = time_limit - timer.split(); Duration time_remaining = time_limit - timer.split();
keep_trying = (mxs_mysql_is_net_error(errornum) && (time_remaining.secs() > 0)); keep_trying = (time_remaining.secs() > 0)
// either a connector-c timeout
&& (mxs_mysql_is_net_error(errornum)
// or query was interrupted by max_statement_time.
|| (!cmd_prefix.empty() && errornum == ER_STATEMENT_TIMEOUT));
if (!cmd_success) if (!cmd_success)
{ {
if (keep_trying) if (keep_trying)
{ {
MXS_WARNING("Query '%s' failed on '%s': %s Retrying with %.1f seconds left.", MXS_WARNING("Query '%s' timed out on '%s': Retrying with %.1f seconds left.",
cmd.c_str(), name(), error_msg.c_str(), time_remaining.secs()); command.c_str(), name(), time_remaining.secs());
if (query_time < min_query_time) if (query_time < min_query_time)
{ {
Duration query_sleep = min_query_time - query_time; Duration query_sleep = min_query_time - query_time;
@ -205,8 +224,7 @@ bool MariaDBServer::execute_cmd_time_limit(const std::string& cmd, maxbase::Dura
} }
else if (errmsg_out) else if (errmsg_out)
{ {
*errmsg_out = string_printf("Query '%s' failed on '%s': %s", *errmsg_out = error_msg; // The error string already has all required info.
cmd.c_str(), name(), error_msg.c_str());
} }
} }
} }