@startuml

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participant "E20 main thread" as main
participant "tdm thread" as sub

sub <-- : a synchronous event
activate sub
--> main: a synchronous event
activate main
sub -> sub: calling thread callbacks in tdm-thread
activate sub
deactivate sub
sub --> main: sending a synchronous event
sub -> sub: pthread_cond_wait
activate sub
main -> main: calling thread callbacks in main-thread
activate main
deactivate main
main --> sub: sending a synchronous event
main -> main: pthread_cond_wait
activate main
deactivate sub
deactivate main
deactivate main
deactivate sub

... <color #red>(DEADLOCK)</color> ...

@enduml