manually clean rocprofiler.pid in RdcWrapper (#323)

Summary:
Pull Request resolved: #323

rocprofiler.pid is a lock used by rocprofiler to guarantee exclusive access by a single process. the lock will be created the first time instantiate rocprofiler but will not be cleaned up by rdc_shutdown() function

for now, we will need to manually remove this lock

Reviewed By: jj10306

Differential Revision: D65249799

fbshipit-source-id: f23f970fe1ad81a77ace217b4bf4598c1c788e3d

dynolog/src/gpumon/amd/RdcWrapper.cpp

@@ -3,6 +3,7 @@
 #include "dynolog/src/gpumon/amd/RdcWrapper.h"
 
 #include <glog/logging.h>
+#include <fstream>
 #include <mutex>
 
 namespace dynolog {
@@ -113,6 +114,26 @@ void RdcWrapper::clean_(RdcRuntimeContextWithWLock& context) {
   if (result != RDC_ST_OK) {
     LOG(WARNING) << "rdc_shutdown() failed with error code: " << result;
   }
+
+  static const char* rocprofilerLockPath = "/tmp/rocprofiler.pid";
+  std::ifstream rocprofilerLock(rocprofilerLockPath);
+  if (rocprofilerLock.fail()) {
+    // rdc may not start rocprofiler
+    // it's fine if the lock file doesn't exist
+    return;
+  }
+  pid_t rocprofilerPid = -1;
+  if (rocprofilerLock >> rocprofilerPid) {
+    if (rocprofilerPid == getpid()) {
+      LOG(INFO) << "remove rocprofiler.pid";
+      if (std::remove(rocprofilerLockPath) != 0) {
+        LOG(ERROR) << "failed to remove rocprofiler lock at "
+                   << rocprofilerLockPath;
+      }
+    }
+  } else {
+    LOG(WARNING) << "failed to read pid from rocprofiler lock file";
+  }
 }
 
 RdcMetricsMap RdcWrapper::getRdcMetricsForDevice(size_t device) {