set follow configurations for some command key:

hystrix.command.fallbackcmd.execution.isolation.thread.timeoutInMilliseconds = 1000000000
hystrix.command.fallbackcmd.execution.isolation.strategy = SEMAPHORE
hystrix.command.fallbackcmd.execution.isolation.semaphore.maxConcurrentRequests = 1000
hystrix.command.fallbackcmd.fallback.enabled = true
hystrix.command.fallbackcmd.circuitBreaker.enabled = true

when it invoke TimerReference.clear(), it does not remove this thread from the queue in ScheduledThreadPoolExecutor,In the case of a large number of requests for long time under this hystrix command key will cause memory leak ,we encounter this problem at our production environment,it Influences service performance