# Unexpected traffic latency or outage on a Security Gateway / Cluster after policy installation

**Product**: Security Gateways  
**Version**: R81.10 (EOS), R81.20  
**OS**: Gaia  
**Last Modified**: 2026-06-16

## Symptoms

- Unexpected traffic latency or outages on a Security Gateway / Cluster when the Firewall is configured to work in the User Space (USFW, see [sk167052](https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk167052)).

- Usually, the issue starts after a policy installation or a signature load.

- During the time of the incident, the output of the "`top`" / "`ps`" command shows that the "`fwk_wd`" process consumes the CPU at high level.

- During the time of the incident, the _/var/log/messages_ file on the Security Gateway contains these three messages repeatedly:
    
    ```
    kernel: [SIM<ID>];cpaq_cbuf_send: cpaq_cbuf_call_api_end_ex failed
    kernel: [SIM<ID>];cpaq_cbuf_send_buffer: send chunk num 0 failed
    kernel: [SIM<ID>];sim_cphwd_stats_cb: failed to create cpaq buffer
    ```

- During the time of the incident, the _/var/log/thread_blocker_device64.log_ file on the Security Gateway contains soft lockups.

- During the time of the incident, the _\$FWDIR/log/fwk_wd.elg_ file on the Security Gateway contains these messages, repeatedly:
    
    ```
    thread_blocker_monitor_periodic_timeout_exp_check: tid  exceeded its timeout(10000)
    thread_blocker_monitor_periodic_timeout_exp_check: cur_time:  reporting_time:
    ```

## Solution

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#### NOTE

This solution has been verified for the specific scenario, described by the combination of Product, Version and Symptoms. It may not work in other scenarios.

## Article Properties

**Access Level**: Advanced  
**Status**: Approved by TAC  
**Date Created**: 2022-12-22  
**Last Modified**: 2026-06-16