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SQL STATE ERROR FIX:

The following approaches were taken to fix SQL State Error 08S01 (JDBC Connection Error: Communication link failure):

  • Increase connection pool size (hibernate. config)

  • Check thoroughly if the connection where we are getting data from db is closed or not

  • Update app-engine service config instance to automatic (F41G)

1runtime: java8 2api_version: user_defined 3env: standard 4threadsafe: true 5instance_class: F4_1G 6inbound_services: 7 - warmup 8handlers: 9 - url: (/.*) 10 static_files: __static__\1 11 require_matching_file: true 12 upload: __NOT_USED__ 13 - url: / 14 script: unused 15 - url: .*\.jsp 16 script: unused 17 - url: /.*/ 18 script: unused 19 - url: /_ah/.* 20 script: unused 21env_variables: 22 ENDPOINTS_SERVICE_NAME: order-return-dot-eshopbox-client-portal-prod.appspot.com 23 GAE_PROFILER_MODE: 'cpu,heap' 24 HEAP_SIZE_RATIO: '90' 25 JAVA_GC_OPTS: '-XX:+UseG1GC -XX:+UseStringDeduplication' 26 JAVA_OPTS: '-XX:-OmitStackTraceInFastThrow' 27automatic_scaling: 28 min_idle_instances: 2 29 max_idle_instances: 2 30 min_pending_latency: automatic 31 max_pending_latency: 15s 32 max_concurrent_requests: 70 33 target_cpu_utilization: 0.9 34 min_instances: 4 35 max_instances: 10 36network: 37 name: default 38vpc_access_connector: 39 name: >- 40 projects/eshopbox-client-portal-prod/locations/asia-south1/connectors/redis-connector-cp 41 egress_setting: private-ip-ranges 42service_account: eshopbox-client-portal-prod@appspot.gserviceaccount.com

  • Change config to c3p0:

1<property name="hibernate.c3p0.min_size">1</property> 2<property name="hibernate.c3p0.max_size">70</property> 3<property name="hibernate.c3p0.timeout">0</property> 4<property name="hibernate.c3p0.max_statements">30</property> 5<property name="hibernate.c3p0.maxConnectionAge">180</property>

  • Update and check the query (log where SQL State Error occurs)

  • Increase database timeout time

  • Enable the 'autoReconnect=true' property in your JDBC connection

  • the 'wait_timeout' setting has increased (36000) 'eshopbox-wms-production' DB instance and its replicas.

  • hibernate.c3p0.maxConnectionAge or the hibernate.c3p0.timeout is below 300 seconds

  • 1<dependency> 2 <groupId>org.hibernate</groupId> 3 <artifactId>hibernate-c3p0</artifactId> 4 <version>6.1.6.Final</version> 5 <type>pom</type> 6</dependency>

    pom.xml add <type>pom</type>

  • Additionally, Google team asked to add following

    1<property name="hibernate.c3p0.unreturnedConnectionTimeout">30</property> 2<property name="hibernate.c3p0.debugUnreturnedConnectionStackTraces">true</property>