> For the complete documentation index, see [llms.txt](https://docs.openiam.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.openiam.com/troubleshooting/performance/jdbc-connection-pool.md).

# Increasing the JDBC connection pool size

Raising the JDBC connection pool size when load testing exhausts it, and where to set it on each deployment type.

| Symptom                                                               | Likely cause                                                             | Resolution                                                                       |
| --------------------------------------------------------------------- | ------------------------------------------------------------------------ | -------------------------------------------------------------------------------- |
| `Unable to acquire JDBC Connection` under load, with requests failing | The pool is exhausted — more concurrent work than it has connections for | [Size the pool](#size-the-pool) and set it on the services that use the database |

## Symptom

Under sustained load — a stress test against `/idp/rest/api/auth/public/login`, for example — requests begin failing with a JPA transaction error whose root cause is the pool:

{% code overflow="wrap" expandable="true" %}

```
javax.xml.ws.soap.SOAPFaultException: Could not open JPA EntityManager for transaction; nested exception is org.hibernate.exception.JDBCConnectionException: Unable to acquire JDBC Connection
 at org.apache.cxf.jaxws.JaxWsClientProxy.mapException(JaxWsClientProxy.java:195) ~[cxf-rt-frontend-jaxws-3.3.6.jar:3.3.6]
 at com.sun.proxy.$Proxy244.getLoginByManagedSys(Unknown Source) ~[?:?]
 at org.openiam.ui.rest.api.mvc.AuthenticationRestController.loginPost(AuthenticationRestController.java:332) ~[classes/:?]
```

{% endcode %}

The deployment it was first seen on had four reverse proxies balancing their own `openiam-ui` instances across three backends, driven at roughly 5,000 requests a second.

## Size the pool

The shipped default is **20**, from `application.common.properties`. A starting point for a load test:

```
Concurrent users: X
TPS per user: 1.5
Avg query time: 0.5 seconds
Pool Size = (X * 1.5 * 0.5) * 1.2
```

{% hint style="info" %}
**Set it on the services that talk to the database** — `openiam-esb`, `openiam-auth` and `workflow`. Two services ship a lower value of their own: `risk-manager` and `privacy-manager` set `5` in their own `application.properties`, and raising the common default does not change them.
{% endhint %}

## Apply it

{% tabs %}
{% tab title="RPM" %}
{% stepper %}
{% step %}
**Point the service at a properties file.** Add this `-D` argument to `services/start_esb.sh`, alongside the ones already there:

{% code overflow="wrap" %}

```bash
-Dspring.config.location=$HOME_DIR/conf/application.esb.properties
```

{% endcode %}
{% endstep %}

{% step %}
**Create that file** with the value you calculated:

{% code title="conf/application.esb.properties" %}

```properties
org.openiam.jdbc.connection.pool.size.max=25
```

{% endcode %}

To watch the pool while testing, add this line as well:

```properties
logging.level.com.zaxxer.hikari=DEBUG
```

{% endstep %}

{% step %}
**Restart the service**, and confirm the old process is gone — a surviving process still holds the old pool.
{% endstep %}

{% step %}
**Check the value took.** With Hikari at `DEBUG`, the configuration is printed at startup. These are the lines that matter:

{% code overflow="wrap" %}

```
com.zaxxer.hikari.HikariConfig  : maximumPoolSize.................25
com.zaxxer.hikari.HikariConfig  : minimumIdle.....................25
com.zaxxer.hikari.pool.HikariPool : HikariPool-1 - Pool stats (total=1, active=0, idle=1, waiting=0)
```

{% endcode %}

`waiting` climbing above zero during a test means the pool is still too small.
{% endstep %}
{% endstepper %}
{% endtab %}

{% tab title="Kubernetes" %}
Java options are held per service in `terraform.tfvars`, under a `javaOpts` block with an entry for each service and a `global` entry:

{% code title="terraform.tfvars" %}

```hcl
javaOpts = {
  global      = "..."
  esb         = "-Dorg.openiam.jdbc.connection.pool.size.max=25"
  authmanager = "..."
}
```

{% endcode %}

Then apply:

```bash
terraform apply
```

{% endtab %}
{% endtabs %}


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