Fix deadlock when running shards on Android (#1853)

maestro-cli/src/main/java/maestro/cli/session/MaestroSessionManager.kt

@@ -71,7 +71,6 @@ object MaestroSessionManager {
         val heartbeatFuture = executor.scheduleAtFixedRate(
             {
                 try {
-                    Thread.sleep(1000) // Add a 1-second delay here for fixing race condition
                     SessionStore.heartbeat(sessionId, selectedDevice.platform)
                 } catch (e: Exception) {
                     logger.error("Failed to record heartbeat", e)

maestro-client/src/main/java/maestro/drivers/AndroidDriver.kt

@@ -50,6 +50,7 @@ import java.net.URI
 import java.util.UUID
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.Executors
+import java.util.concurrent.Semaphore
 import java.util.concurrent.TimeUnit
 import java.util.concurrent.TimeoutException
 import javax.xml.parsers.DocumentBuilderFactory
@@ -72,6 +73,7 @@ class AndroidDriver(
     private val blockingStubWithTimeout get() = blockingStub.withDeadlineAfter(40, TimeUnit.SECONDS)
     private val asyncStub = MaestroDriverGrpc.newStub(channel)
     private val documentBuilderFactory = DocumentBuilderFactory.newInstance()
+    private val deviceCallSemaphore = Semaphore(1)
 
     private var instrumentationSession: AdbShellStream? = null
     private var proxySet = false
@@ -1093,6 +1095,7 @@ class AndroidDriver(
     }
 
     private fun <T> runDeviceCall(call: () -> T): T {
+        deviceCallSemaphore.acquire()
         return try {
             call()
         } catch (throwable: StatusRuntimeException) {
@@ -1102,6 +1105,8 @@ class AndroidDriver(
                 throw MaestroException.DriverTimeout("Android driver unreachable")
             }
             throw throwable
+        } finally {
+            deviceCallSemaphore.release()
         }
     }