Connection error ? A lot of Error scraping

[Jean-MarcS]

Host operating system: output of uname -a

Linux mysql 4.15.18-13-pve #1 SMP PVE 4.15.18-37 (Sat, 13 Apr 2019 21:09:15 +0200) x86_64 GNU/Linux

mysqld_exporter version: output of mysqld_exporter --version

Last one from July 2019

MySQL server version

10.4.13-MariaDB-1:10.4.13+maria~buster-log

mysqld_exporter command line flags

ExecStart=/usr/local/bin/mysqld_exporter
--config.my-cnf /etc/.mysqld_exporter.cnf
--collect.auto_increment.columns
--collect.binlog_size
--collect.global_status
--collect.global_variables
--collect.info_schema.innodb_metrics
--collect.info_schema.processlist
--collect.info_schema.tablestats
--collect.info_schema.query_response_time
--collect.info_schema.tables
--collect.info_schema.userstats
--collect.perf_schema.eventswaits
--collect.perf_schema.file_events
--collect.perf_schema.indexiowaits
--collect.perf_schema.tableiowaits
--collect.perf_schema.tablelocks
--exporter.lock_wait_timeout 10
--web.listen-address=0.0.0.0:9104

What did you do that produced an error?

Just installed and run it

What did you expect to see?

Not that much errors, and unfragmented graphs

What did you see instead?

Lots of error in my logs

For example :

Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.perf_schema.file_events: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.info_schema.innodb_cmpmem: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.perf_schema.tablelocks: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.binlog_size: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.info_schema.query_response_time: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.perf_schema.indexiowaits: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.info_schema.tables: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.slave_status: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.info_schema.innodb_cmp: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.perf_schema.tableiowaits: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:41+02:00" level=error msg="Error scraping for collect.perf_schema.eventswaits: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:41 mysql mysqld[17375]: 2020-06-15 12:33:41 106002 [Warning] Aborted connection 106002 to db: 'unconnected' user: 'mysqld_exporter' host: '192.168.1.200' (Got an error writing communication packets) Jun 15 12:33:56 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:56+02:00" level=error msg="Error scraping for collect.info_schema.userstats: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:56 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:56+02:00" level=error msg="Error scraping for collect.info_schema.tables: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:56 mysql mysqld_exporter[23547]: time="2020-06-15T12:33:56+02:00" level=error msg="Error scraping for collect.info_schema.innodb_cmpmem: context deadline exceeded" source="exporter.go:171" Jun 15 12:33:57 mysql mysqld[17375]: 2020-06-15 12:33:57 106026 [Warning] Aborted connection 106026 to db: 'unconnected' user: 'mysqld_exporter' host: '192.168.1.200' (Got an error writing communication packets) Jun 15 12:33:58 mysql mysqld_exporter[23547]: 2020/06/15 12:33:58 http: superfluous response.WriteHeader call from github.com/prometheus/client_golang/prometheus/promhttp.(*responseWriterDelegator).WriteHeader (delegator.go:58)

The exporter is on the same VM than the MariaDB server, connecting via local IP 192.168.1.200.

I have some datas, but a LOT of gaps in my metrics.

MySQL's user is configured with MAX_USER_CONNECTIONS=5 (2 was advised in the tutorial I used)

Any idea of what could cause those error (and if there is a way to correct that) ?

Thanks !

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[ragsarang]

I was facing this issue due to max connections reached. I increased the max_connections parameter in database and then released some connections.
It was able to scrape again.