Signals - Failed to start thread - pthread_create failed (EAGAIN)

Elasticsearch version:
7.8
Server OS version:
Centos 7
Kibana version (if relevant):
7.8
Browser version (if relevant):

Browser OS version (if relevant):

Describe the issue:
I have problem to start more instances of elasticsearch containers on the same machine. When i disable signals in elasticsearch.yml i can run more containers.
Could You provide me some info what can be a reason?

Log from instance

Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: [12.360s][warning][os,thread] Failed to start thread - pthread_create failed (EAGAIN) for attributes: stacksize: 1024k, guardsize: 0k, deta
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: fatal error in thread [Thread-5], exiting
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: java.lang.OutOfMemoryError: unable to create native thread: possibly out of memory or process/resource limits reached
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at java.base/java.lang.Thread.start0(Native Method)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at java.base/java.lang.Thread.start(Thread.java:801)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at org.quartz.simpl.SimpleThreadPool.initialize(SimpleThreadPool.java:277)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.searchsupport.jobs.SchedulerBuilder.buildImpl(SchedulerBuilder.java:239)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.searchsupport.jobs.SchedulerBuilder.build(SchedulerBuilder.java:232)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.signals.SignalsTenant.init(SignalsTenant.java:138)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.signals.SignalsTenant.create(SignalsTenant.java:78)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.signals.Signals.createTenant(Signals.java:255)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.signals.Signals.updateTenants(Signals.java:363)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.signals.Signals.access$300(Signals.java:56)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.signals.Signals$2.onChanged(Signals.java:453)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.searchguard.sgconf.DynamicConfigFactory.onChange(DynamicConfigFactory.java:177)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.searchguard.configuration.ConfigurationRepository.notifyAboutChanges(ConfigurationRepository.java:337)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.searchguard.configuration.ConfigurationRepository.reloadConfiguration0(ConfigurationRepository.java:291)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.searchguard.configuration.ConfigurationRepository.reloadConfiguration(ConfigurationRepository.java:274)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at com.floragunn.searchguard.configuration.ConfigurationRepository$1.run(ConfigurationRepository.java:191)
Jul 13 16:05:08 esdata2 systemd-entrypoint[2441]: at java.base/java.lang.Thread.run(Thread.java:832)

best regards

java.lang.OutOfMemoryError: unable to create native thread: possibly out of memory or process/resource limits reached

Increase the Java memory: https://stackoverflow.com/q/27359885/2393924