# MQTT Library and SEMI\_AUTOMATIC

**URL:** <https://community.particle.io/t/mqtt-library-and-semi-automatic/22875>\
**Category:** Troubleshooting\
**Created:** [May 13, 2016, 1:25pm UTC](https://community.particle.io/t/mqtt-library-and-semi-automatic/22875 "2016-05-13T13:25:00Z")\
**Posts on this page:** 1\
**Showing post:** 25

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**Author:** ![dreamER](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/dreamer/32/26550_2.png) [@dreamER](https://community.particle.io/u/dreamER)\
**Post date:** [July 22, 2021, 5:59pm UTC](https://community.particle.io/t/mqtt-library-and-semi-automatic/22875/25 "2021-07-22T17:59:36Z")

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hi,  
If you running `SYSTEM_THREAD(ENABLED)` you have to set 4-th parameter in your client initialization  
`MQTT client("sample.com", 1883, callback, true);`  
here from official example:  
 ![sys_thread_en](https://us1.discourse-cdn.com/flex026/uploads/particle/original/3X/b/5/b59e9129ed9fc69aeaf057ae108f4ad34fac65cc.jpeg)

In this case even if your broker is not available the code will not block 😜

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