GCP PostgreSQL instance database flag log_lock_waits is disabled

Description

Deadlock timeout defines the time to wait on a lock before checking for any conditions. Frequent runovers on deadlock timeout can be an indication of an underlying issue. Log these waits on locks using the log_lock_waits database flag and use the information to identify poor performance due to locking delays, or if a specially-crafted SQL is attempting to starve resources through holding locks for excessive amounts of time.

We recommended you set the log_lock_waits flag for a PostgreSQL instance to On. This will create a log for any session and allow you to identify waits that take longer than the allotted deadlock_timeout time to acquire a lock.

Fix - Runtime Remediation

GCP Console

To change the policy using the GCP Console, follow these steps:

1. Log in to the GCP Console at https://console.cloud.google.com.
2. Navigate to Cloud SQL Instances.
3. Select the PostgreSQL instance where the database flag needs to be enabled.
4. Click Edit.
5. Scroll down to the Flags section.
6. To set a flag that has not been set on the instance before, click Add item.
7. Select the flag log_lock_waits from the drop-down menu, and set its value to On.
8. Click Save.
9. Confirm the changes in the Flags section on the Overview page.

CLI Command

1. List all Cloud SQL database instances using the following command:
   gcloud sql instances list
2. Configure the log_lock_waits database flag for every Cloud SQL PosgreSQL database instance using the below command:
   gcloud sql instances patch INSTANCE_NAME --database-flags log_lock_waits=on

📘 Note

This command will overwrite all database flags previously set. To keep these flags, and add new ones, include the values for all flags to be set on the instance. Any flag not specifically included is set to its default value. For flags that do not take a value, specify the flag name followed by an equals sign (=).

Fix - Buildtime

Terraform

• Resource: google_sql_database_instance
• Arguments:
  database_version = "POSTGRES_* "
  settings::database_flags: key:"log_lock_waits", value: by default set to "off"

resource "google_sql_database_instance" "default" {
  name             = "master-instance"
  database_version = "POSTGRES_11"
  region           = "us-central1"

  settings {
+         database_flags {
+            name  = "log_lock_waits"
+            value = "on"
          }
  }
}