[orchagent] Flush pipeline every 1 second, not only when select will …

…timeout (sonic-net#2003)

* Added flush for async communication pipeline, every 1 second, not only if select will timeout.

orchagent/orchdaemon.cpp

@@ -1,5 +1,6 @@
 #include <unistd.h>
 #include <unordered_map>
+#include <chrono>
 #include <limits.h>
 #include "orchdaemon.h"
 #include "logger.h"
@@ -645,13 +646,26 @@ void OrchDaemon::start()
  m_select->addSelectables(o->getSelectables());
  }
 
+ auto tstart = std::chrono::high_resolution_clock::now();
+
  while (true)
  {
  Selectable *s;
  int ret;
 
  ret = m_select->select(&s, SELECT_TIMEOUT);
 
+ auto tend = std::chrono::high_resolution_clock::now();
+
+ auto diff = std::chrono::duration_cast<std::chrono::milliseconds>(tend - tstart);
+
+ if (diff.count() >= SELECT_TIMEOUT)
+ {
+ tstart = std::chrono::high_resolution_clock::now();
+
+ flush();
+ }
+
  if (ret == Select::ERROR)
  {
  SWSS_LOG_NOTICE("Error: %s!\n", strerror(errno));