Your Client Workers are being maxed out apparently by any reason.

Client Workers get maxed out for many reasons. Here are some common reasons:

• ICAP bottleneck you can take a look on OPP/stat
• DNS issue
• Loop on certain traffic
• Authentication failure or delay
• Proxy upstream network issue
• Box undersize
• Bug
• Clients with malware installed
• An [internal] virus outbreak, or "Bot-net"
• A Trace Rule where the Source or Destination fields are not set
  • Source: Any
  • Destination: Any