當corba服務器進程停止時，客戶端調用被阻止

Question

這裏的問題是corba調用不會返回，並且corba服務器停止時不會引發異常。 在我的情況下，只有一個多線程corba代理（Window），監視一個後端corba服務器。 corba服務器的IDL爲：

  void run() 
      void echo(); 

代理通過echo心跳調用檢查後端的健康狀況。如果在echo中拋出corba異常，代理會將後端分類爲DOWN狀態。此過程在大多數時間都有效，但後端關閉。

1）如果我關閉後端機器，立即回聲拋出異常。

2）如果我停止後端corba進程，echo調用掛起並且不返回，在客戶端沒有異常。客戶不能再走向未來了。

以上兩種情況都不會發生運行調用。

具有'ORBDebugLevel 10'的日誌顯示代理完成迴應請求發送，而netstat showns在代理和後端機器之間執行一個TCP連接，儘管後端corba服務器進程停止（我承認後端服務器是無序的或編程不良）。但是作爲代理，它是如何避免由於個別調用失敗而被阻塞，如果它既不返回也不拋出異常？

下面是兩個日誌，默認策略：

TAO (276|1592) - Invocation_Adapter::invoke_i, making a TAO_CS_REMOTE_STRATEGY i 
nvocation 
TAO (276|1592) - Transport_Cache_Manager_T::is_entry_available_i[828], true, sta 
te is ENTRY_IDLE_AND_PURGABLE 
TAO (276|1592) - Cache_IntId_T::recycle_state, ENTRY_IDLE_AND_PURGABLE->ENTRY_BU 
SY Transport[828] IntId=00A64ABC 
TAO (276|1592) - Transport_Cache_Manager_T::find_i, Found available Transport[82 
8] @hash:index {-1062676757:0} 
TAO (276|1592) - Transport_Connector::connect, got an existing connected Transpo 
rt[828] in role TAO_CLIENT_ROLE 
TAO (276|1592) - Muxed_TMS[828]::request_id, <4> 
TAO (276|1592) - GIOP_Message_Base::dump_msg, send GIOP message v1.2, 60 data by 
tes, my endian, Type Request[4] 
GIOP message - HEXDUMP 72 bytes 
47 49 4f 50 01 02 01 00 3c 00 00 00 04 00 00 00 GIOP....<....... 
03 00 00 00 00 00 cd cd 1b 00 00 00 14 01 0f 00 ................ 
52 53 54 00 00 00 6c 00 06 9c b5 00 00 00 00 00 RST...l......... 
00 00 01 00 00 00 01 cd 05 00 00 00 65 63 68 6f ............echo 
00 cd cd cd 00 00 00 00       ........ 
TAO (276|1592) - Transport[828]::drain_queue_helper, sending 1 buffers 
TAO (276|1592) - Transport[828]::drain_queue_helper, buffer 0/1 has 72 bytes 
TAO - Transport[828]::drain_queue_helper (0/72) - HEXDUMP 72 bytes 
47 49 4f 50 01 02 01 00 3c 00 00 00 04 00 00 00 GIOP....<....... 
03 00 00 00 00 00 cd cd 1b 00 00 00 14 01 0f 00 ................ 
52 53 54 00 00 00 6c 00 06 9c b5 00 00 00 00 00 RST...l......... 
00 00 01 00 00 00 01 cd 05 00 00 00 65 63 68 6f ............echo 
00 cd cd cd 00 00 00 00       ........ 
TAO (276|1592) - Transport[828]::drain_queue_helper, end of data 
TAO (276|1592) - Transport[828]::cleanup_queue, byte_count = 72 
TAO (276|1592) - Transport[828]::cleanup_queue, after transfer, bc = 0, all_sent 
= 1, ml = 0 
TAO (276|1592) - Transport[828]::drain_queue_helper, byte_count = 72, head_is_em 
pty = 1 
TAO (276|1592) - Transport[828]::drain_queue_i, helper retval = 1 
TAO (276|1592) - Transport[828]::make_idle 
TAO (276|1592) - Cache_IntId_T::recycle_state, ENTRY_BUSY->ENTRY_IDLE_AND_PURGAB 
LE Transport[828] IntId=00A64ABC 
TAO (276|1592) - Leader_Follower[828]::wait_for_event, (follower), cond <00B10DD 
8> 

使用靜態Client_Strategy_Factory " -ORBTransportMuxStrategy EXCLUSIVE "

2014-Sep-03 16:34:26.143024 
TAO (6664|5612) - Invocation_Adapter::invoke_i, making a TAO_CS_REMOTE_STRATEGY 
invocation 
TAO (6664|5612) - Transport_Cache_Manager_T::is_entry_available_i[824], true, st 
ate is ENTRY_IDLE_AND_PURGABLE 
TAO (6664|5612) - Cache_IntId_T::recycle_state, ENTRY_IDLE_AND_PURGABLE->ENTRY_B 
USY Transport[824] IntId=00854ABC 
TAO (6664|5612) - Transport_Cache_Manager_T::find_i, Found available Transport[8 
24] @hash:index {-1062667171:0} 
TAO (6664|5612) - Transport_Connector::connect, got an existing connected Transp 
ort[824] in role TAO_CLIENT_ROLE 
TAO (6664|5612) - Exclusive_TMS::request_id - <3> 
TAO (6664|5612) - GIOP_Message_Base::dump_msg, send GIOP message v1.2, 60 data b 
ytes, my endian, Type Request[3] 
GIOP message - HEXDUMP 72 bytes 
47 49 4f 50 01 02 01 00 3c 00 00 00 03 00 00 00 GIOP....<....... 
03 00 00 00 00 00 cd cd 1b 00 00 00 14 01 0f 00 ................ 
52 53 54 00 00 00 55 00 0d 7a 85 00 00 00 00 00 RST...U..z...... 
00 00 01 00 00 00 01 cd 05 00 00 00 65 63 68 6f ............echo 
00 cd cd cd 00 00 00 00       ........ 
TAO (6664|5612) - Transport[824]::drain_queue_helper, sending 1 buffers 
TAO (6664|5612) - Transport[824]::drain_queue_helper, buffer 0/1 has 72 bytes 
TAO - Transport[824]::drain_queue_helper (0/72) - HEXDUMP 72 bytes 
47 49 4f 50 01 02 01 00 3c 00 00 00 03 00 00 00 GIOP....<....... 
03 00 00 00 00 00 cd cd 1b 00 00 00 14 01 0f 00 ................ 
52 53 54 00 00 00 55 00 0d 7a 85 00 00 00 00 00 RST...U..z...... 
00 00 01 00 00 00 01 cd 05 00 00 00 65 63 68 6f ............echo 
00 cd cd cd 00 00 00 00       ........ 
TAO (6664|5612) - Transport[824]::drain_queue_helper, end of data 
TAO (6664|5612) - Transport[824]::cleanup_queue, byte_count = 72 
TAO (6664|5612) - Transport[824]::cleanup_queue, after transfer, bc = 0, all_sen 
t = 1, ml = 0 
TAO (6664|5612) - Transport[824]::drain_queue_helper, byte_count = 72, head_is_e 
mpty = 1 
TAO (6664|5612) - Transport[824]::drain_queue_i, helper retval = 1 
TAO (6664|5612) - Leader_Follower[824]::wait_for_event, (follower), cond <009009 
10> 

我理解這可能是螺紋和ORB模型的問題。我嘗試了一些客戶的策略：

靜態Client_Strategy_Factory「-ORBTransportMuxStrategy EXCLUSIVE -ORBClientConnectionHandler RW」

這樣可以減少問題發生的頻率，但解決不了問題完整。

---

這和我6年前的經驗很相似。在這種情況下，調用是在客戶端的一個線程中發送的。在接收到響應之前，由於反應堆模式，該線程被重新用於發送另一個corba請求。這個案例似乎不同於這裏的案例，因爲它只是一個corba調用。我的線程堆棧的印象是有點像：

server.anotherInvocation() //the thread is used for another invocation. 
... 
server::echo() //send 1st corba invocation 
.... 
orb-run() 

Answer 1

的問題是，它是依賴於操作系統的，當網絡堆棧將檢測服務器斷開連接，有時它永遠不會發生。設置RELATIVE_RT_TIMEOUT_POLICY_TYPE策略以強制調用超時更好也更安全，請參閱ACE_wrappers/TAO/tests/Timeout以獲取示例。