[Qemu-devel] [Bug 1585533] Re: cache-miss-rate / Invalid JSON

[Thomas Huth]

Is there still something to be done for upstream QEMU here? ...
otherwise, I assume we can close this bug now?

** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1585533

Title:
  cache-miss-rate / Invalid JSON

Status in QEMU:
  Incomplete

Bug description:
  Hi,

  We have VMs which were started with an older version than qemu 2.1
  which added "cache-miss-rate" property for XBZRLECacheStats. While
  trying to migrate the VM to a new host which is running a higher
  version (2.3) of Qemu we got an exception:

  virJSONValueFromString:1642 : internal error: cannot parse json {"return": 
{"expected-downtime": 1, "xbzrle-cache": {"bytes": 0, "cache-size": 67108864, 
"cache-miss-rate": -nan, "pages": 0, "overflow": 0, "cache-miss": 8933}, 
"status": "active", "disk": {"total": 429496729600, "dirty-sync-count": 0, 
"remaining": 193896382464, "mbps": 0, "transferred": 235600347136, "duplicate": 
0, "dirty-pages-rate": 0, "skipped": 0, "normal-bytes": 0, "normal": 0}, 
"setup-time": 13, "total-time": 1543124, "ram": {"total": 8599183360, 
"dirty-sync-count": 4, "remaining": 30695424, "mbps": 830.636997, 
"transferred": 3100448901, "duplicate": 1358341, "dirty-pages-rate": 7, 
"skipped": 0, "normal-bytes": 3082199040, "normal": 752490}}, "id": 
"libvirt-186200"}: lexical error: malformed number, a digit is required after 
the minus sign.
            67108864, "cache-miss-rate": -nan, "pages": 0, "overflow": 0
                       (right here) ------^

  virNetClientStreamRaiseError:191 : stream aborted at client request

  
  Would it be possible to improve the JSON parser to skip the key if the value 
is incorrect instead of throwing an exception? Then hopefully qemu 2.3 or 
higher is able to handle the data without this property, falling back to its 
default.

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