Load Control Device and Method Thereof

• US 20090077233A1
• Filed: 04/25/2007
• Published: 03/19/2009
• Est. Priority Date: 04/26/2006
• Status: Active Grant

• Current Assignee: Nippon Telegraph and Telephone Corporation
• Original Assignee: Nippon Telegraph and Telephone Corporation
• Inventors: Ota, Satoru, Ishida, Osamu, Obana, Kazuaki, Hayashi, Tsunemasa, Kurebayashi, Ryosuke
• Granted Patent: US 8,667,120 B2
• Time in Patent Office: Days
• US Class Current: 709/224
• CPC Class Codes: G06F 9/4843 by program, e.g. task dispatcher, supervisor, operating system
• CPC Class Codes: H04L 41/0896 Bandwidth or capacity management, i.e. automatically increasing or decreasing capacities flow or congestion control using dynamic resource allocation, e.g. in-call renegotiation, H04L47/76
• CPC Class Codes: H04L 43/0894 Packet rate
• CPC Class Codes: H04L 43/16 Threshold monitoring
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/193 at the transport layer, e.g. TCP related
• CPC Class Codes: H04L 47/27 Evaluation or update of window size, e.g. using information derived from acknowledged [ACK] packets
• CPC Class Codes: H04L 47/39 Credit based
• CPC Class Codes: H04L 67/60 Scheduling or organising the servicing of application requests, e.g. requests for application data transmissions using the analysis and optimisation of the required network resources admission control or resource allocation H04L47/70
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/165 Combined use of TCP and UDP protocols; selection criteria therefor

Abstract

The number of response-waiting requests which are already sent to a server (4) but to which a response is not yet returned from the server (4) is limited. To limit this number, received requests are temporarily accumulated in a buffer if the number of response-waiting requests has reached a threshold and, until the number of response-waiting requests falls below the threshold, requests are not sent from the buffer. The execution status of the server (4) is monitored, and the threshold is increased when the response time from the server (4) to a request is within an allowable range, and the threshold is decreased when the response time exceeds the allowable range. In addition, TCP connections between a load control device (3) and clients (1-1, 1-n) are aggregated so that the number of simultaneous connections of TCP connections between the server (4) and the load control device (3) becomes equal to or smaller than the threshold of the number of response-waiting requests.

Claims

1. A load control device, provided between clients and a server, for sending a request, received from said clients, to said server and for sending a response, returned from said server in response to the request, to said clients, said load control device comprising:

means that limits a number of response-waiting requests which are already sent to said server but to which responses are not yet returned from said server, wherein

the means that limits the number comprises;

a buffer in which received requests are temporarily accumulated if the number of response-waiting requests has reached a threshold; and

means that does not send a request from said buffer until the number of response-waiting requests falls below the threshold.

2. The load control device according to claim 1 wherein the threshold is a value larger than 1.

3. The load control device according to claim 1, further comprising:

monitoring means that monitors an execution status of said server; and

means that increases the threshold of the number of response-waiting requests when a response time of said server to a request is within an allowable range, and decreases the threshold of the number of response-waiting requests when the response time exceeds the allowable range, based on a monitor result of said monitoring means.

4. The load control device according to claim 1, further comprising:

monitoring means that monitors an execution status of said server;

means that measures throughput for each threshold of the number of response-waiting requests based on a monitor result of said monitoring means, said throughput being a number of requests processed by said server per unit time; and

means that increases the threshold if throughput for a current threshold is higher than throughput for a threshold lower than the current threshold and decreases the threshold if throughput for the current threshold is lower than throughput for a threshold lower than the current threshold.

5. The load control device according to claim 3, further comprising:

means that determines if the number of response-waiting requests has reached the threshold; and

means that determines whether or not the threshold is to be increased or decreased if the threshold is reached.

6. The load control device according to claim 1, further comprising means that aggregates TCP connections between itself and said clients so that a number of simultaneous connections of TCP connections between said server and itself becomes equal to or smaller than the threshold of the number of response-waiting requests.

7. The load control device according to claim 1 wherein said buffer comprises means that performs priority control of requests based on identification information on said sending clients.

8. The load control device according to claim 1 wherein said buffer comprises means that performs priority control of requests based on whether or not a particular pattern is included in a particular position or range in a request.

9. The load control device according to claim 1 wherein said buffer comprises means that performs priority control of requests based on whether or not a particular variable in a request is larger than a pre-set threshold.

10. The load control device according to claim 1 wherein said buffer comprises means that performs priority control of requests based on whether or not a request is encrypted.

11. The load control device according to claim 1 wherein said buffer comprises means that notifies a busy message to a request accumulated for a predetermined time or longer.

12. The load control device according to claim 1 wherein said server is a Web server and

said buffer comprises means that performs priority control of requests based on display priority of a page display of requests.

13. The load control device according to claim 1 wherein the request is sent from said clients to said load control device via a TCP connection and

said buffer comprises means that performs priority control of requests based on whether or not another TCP connection is established between said clients and said load control device, a number of TCP connections, or whether or not the request is a first request of a TCP connection.

14. The load control device according to claim 1, further comprising:

means that, when the response contains a URL of a page component to be automatically acquired by a browser, temporarily stores a set of identification information on a response-sending destination and the URL wherein

said buffer comprises means that performs priority control of requests based on whether or not a set of identification information on a request sending-source and a URL matches said set of identification information on a response-sending destination and the URL that is temporarily stored.

15. The load control device according to claim 1, further comprising means that performs priority control of requests based on a progress status of a session to which said request belongs.

16. The load control device according to claim 1, further comprising:

means that caches session identification information on a session, to which a request processed by said server belongs, for a fixed period of time; and

means that performs priority control of requests based on whether or not the request has the identification information on a session that is cached.

17. The load control device according to claim 1 wherein said buffer comprises means that performs priority control of requests based on degree of suspicion of unauthorized access of traffic sent from said clients.

18. A program that is installed in a general-purpose information processing device and that causes said general-purpose information processing device to implement a function equivalent to a function of the load control device according to one of claims 1-17.

19. A recording medium on which the program according to claim 18 is recorded and which is readable by said general-purpose information processing device.

26. The load control device according to claim 4, further comprising:

means that determines if the number of response-waiting requests has reached the threshold; and

means that determines whether or not the threshold is to be increased or decreased if the threshold is reached.

20. A load control method for execution by a load control device, provided between clients and a server, for sending a request, received from said clients, to said server and for sending a response, returned from said server in response to the request, to said clients, said load control method comprising:

a limiting step of limiting a number of response-waiting requests which are already sent to said server but to which responses are not yet returned from said server, wherein

the limiting step comprises;

a step of temporarily accumulating received requests in a buffer if the number of response-waiting requests has reached a threshold; and

a step of not sending a request from said buffer until the number of response-waiting requests falls below the threshold.

21. The load control method according to claim 20 wherein the threshold is a value larger than 1.

22. The load control method according to claim 20, further comprising:

a monitoring step of monitoring an execution status of said server; and

a step of increasing the threshold of the number of response-waiting requests when a response time of said server to a request is within an allowable range, and decreasing the threshold of the number of response-waiting requests when the response time exceeds the allowable range, based on a monitor result of said monitoring step.

23. The load control method according to claim 20, further comprising:

a monitoring step of monitoring an execution status of said server (4);

a step of measuring throughput for each threshold of the number of response-waiting requests based on a monitor result of said monitoring step, said throughput being a number of requests processed by said server per unit time; and

a step of increasing the threshold if throughput for a current threshold is higher than throughput for a threshold lower than the current threshold and decreasing the threshold if throughput for the current threshold is lower than throughput for a threshold lower than the current threshold.

24. The load control method according to claim 22, further comprising:

a step of determining if the number of response-waiting requests has reached the threshold; and

a step of determining whether or not the threshold is to be increased or decreased if the threshold is reached.

25. The load control method according to claim 20, further comprising a step of aggregating TCP connections between itself (3) and said clients so that a number of simultaneous connections of TCP connections between said server and itself becomes equal to or smaller than the threshold of the number of response-waiting requests.

27. The load control method according to claim 23, further comprising:

a step of determining if the number of response-waiting requests has reached the threshold; and

a step of determining whether or not the threshold is to be increased or decreased if the threshold is reached.