KR20000037793A - Method of ordering events for re-executing distribution system - Google Patents

Abstract

PURPOSE: A method of ordering events for re-executing a distribution system is provided to reduce a data capacity requested for re-execution, and to minimize a delay time, by obtaining a minimum events order set which should be ordered. CONSTITUTION: A method of ordering events for re-executing a distribution system comprises the steps of: generating an event diagram displayed a relation of the events, which is generated from a performing procedure of the system, by recording the performance by use of a monitoring server and a center monitor; extracting an event order for ensuring proper re-execution, by analysing the generated diagram; and repeating a same re-execution, while controlling keeping the event order.

Description

The event ordering method for replaying distributed systems

The present invention relates to an event sequencing method for ensuring correct retry of a distributed system. More particularly, the present invention relates to a method of ensuring that a source performance of a non-deterministic distributed program is repeated through the control of an event sequence.

In general, distributed systems are characterized by the fact that their performance is indeterminate due to the parallelism of communications and processes.

This non-deterministic nature is the biggest reason that makes debugging and testing a system difficult. This is because nondeterministic performance cannot show the cause of error by reproducing the situation of error by showing different performance paths and results. One way to debug such a system is to rerun non-deterministic executions so that the same executions are repeated.

To ensure correct retry, it is necessary to ensure that all events that occur during the execution of the distributed system are repeated in the same order.

The retrying method of the conventional distributed system assures that the sequence of all events is retried as it is, which has a problem that the number of events is too large and the additional delay for the control and the additional burden of the control are too large. In practice, however, it is not necessary to keep all events in order, and the key dependency in a distributed system is only 5-10% of the total number of events.

The present invention has been made to solve the problems of the prior art as described above, and relates to a method for extracting only the sequence of necessary events by analyzing the source performance of the distributed system. At this time, the set of events is the minimum set of event sequences for correctly retrying the performance of the non-deterministic distributed system.

1 is a schematic configuration diagram of a distributed processing diagnosis / calibration apparatus for explaining an embodiment of the present invention.

2 is a signal flowchart illustrating a method of simultaneously starting a distributed debugging function according to an embodiment of the present invention.

♠ Explanation of symbols on the main parts of the drawing ♠

100: client (central monitor)

110-1 to 110-N: First to Nth host computers

120-1 to 120-N: 1st to Nth monitoring server

130-1 to 13-N: 1st to Nth distributed processes

According to the present invention for achieving the object as described above, in the event sequencing method of the distributed system to perform a non-deterministic performance, by recording the performance of the distributed system using a monitoring server and a central monitor, in the process of performing the distributed system Generating an event diagram indicative of the relationship between the events that have occurred; A second step of analyzing the event diagram generated in the first step and extracting an event sequence for ensuring correct retry of the performance of the distributed system; And a third step of repeating the same retry while controlling to keep the order of the events ordered in the second step, wherein the event sequencing method of the distributed system is provided.

In addition, in a computer-readable recording medium that records a program capable of executing an event sequencing method of a distributed system that performs non-deterministic performance, the performance of the distributed system is recorded by using a monitoring server and a central monitor. A first step of generating an event diagram indicating a relationship between events occurring in an execution process; A second step of analyzing the event diagram generated in the first step to order the non-deterministic received events; A third step of extracting an event sequence for guaranteeing correct retry by ordering transmission events corresponding to reception events ordered in the second step; And a computer-readable recording medium having recorded thereon a program capable of executing the fourth step of repeating the same retry while controlling to keep the transmission event sequence determined in the third step.

In the following, with reference to the accompanying drawings, a preferred embodiment according to the present invention will be described in detail.

1 is a schematic configuration diagram of a distributed system and an event monitoring apparatus applied to an embodiment of the present invention, and FIG. 2 is an example of an event diagram of a distributed system according to an embodiment of the present invention.

As illustrated in FIG. 1, a distributed system and an event monitoring apparatus for explaining an embodiment of the present invention are configured as a central monitor client 100 and N host computers 110-1 to 110 -N. The host computer is composed of a monitoring server 120 and a process 130, respectively. This will be described in detail as follows.

First, when the distributed system (consisting of N processes from 130-1 to 130-N) performs the source, each monitoring server 120 displays the information of the event type, sender, and receiver whenever an event occurs. The analysis is informed to the central monitor 100.

The monitoring server 120 analyzes all occurrence events of the execution process while monitoring the process of the distributed system. The monitoring server 120 may be a separate process or a portion of code that may change the process of the distributed system to handle such a function. It may be added. By analyzing the information of the events collected from the monitoring server in this way, the central monitor 100 may generate an event diagram as shown in FIG.

The event diagram of FIG. 2 is a data structure stored in the form of a graph by the central monitor as information showing a relationship between events generated in a distributed system. This event diagram has all the information to analyze the event dependencies of a distributed system. This data structure can be used to extract the propriety of incoming and outgoing events below.

In the event diagram as shown in FIG. 2 obtained in the above process, the order of received events must first be extracted. The order of receive events may change the order in which they are received in the receive queue when performed due to non-deterministic factors such as communication delays and the speed of execution of other processes.

In other words, once an event is received, the process continues to perform deterministic tasks such as performing internal logic, sending necessary events, and performing I / O, etc. However, the order of execution depends on which event arrives first. What changes is inevitable due to the non-deterministic nature of distributed systems. Therefore, it is necessary and sufficient to ensure that the order of received events is observed in order to re-determinate one source execution.

In FIG. 2, the received event sequence is the sequence of events 21, 23, 25, and 26 in process 200, and the sequence of 32 and 34 in process 300. If the above order is followed, the execution of individual processes is crucial, and thus the event diagram may have the same shape as in FIG. 2.

Next, the transmission events corresponding to these reception events are ordered. As mentioned above, the order of reception events cannot be guaranteed due to factors such as communication delay and execution speed of processes.

However, as the most basic assumption of a distributed system, a receive event cannot occur before the corresponding transmit event occurs. Therefore, in order to keep the order of the reception events A and B, the reception event A may occur after the transmission event A has occurred, and then control may be performed so that the transmission event B is subsequently generated.

Therefore, the order of (A, B) is the order relationship that must be forced for retry. This order relationship becomes the minimum set of order relationships that are essential to the present invention. In FIG. 2, there are five sets of the order relations (12, 24), (21, 13), (23, 33), (25, 15), and (32, 27). However, of these, (12, 24) and (32, 27) do not need to be further ordered because they already have dependencies on the event diagram. After all, in this example, there are three sequence sets of events that must be forcibly controlled.

Next, in order to enforce the sequence relationship obtained as described above, in the present invention, after the reception event A occurs, an additional event is generated to generate a transmission event called C, and the reception event C of C is immediately before the transmission event B. So that the transmission event B can never occur before the reception of A. In this way, by ensuring that the order of the transmit and receive events is the same as when performing the source, it is possible to control the retry to be the correct one with the same result.

The present invention has the effect of reducing the amount of data required for retrying and minimizing the delay time by obtaining a minimum set of event sequences to be ordered for retrying a distributed system.

The technical spirit of the present invention has been described above with reference to the accompanying drawings. However, the present invention has been described by way of example only, and is not intended to limit the present invention. In addition, it is obvious that any person skilled in the art may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (3)

In the event sequencing method of a distributed system that performs nondeterministic execution, A first step of generating an event diagram representing a relationship between events occurring in the execution of the distributed system by recording the performance of the distributed system using the monitoring server and the central monitor; A second step of analyzing the event diagram generated in the first step and extracting an event sequence for ensuring correct retry of the performance of the distributed system; And And a third step of repeating the same retry while controlling to keep the order of the events ordered in the second step. The method of claim 1, The second step, A fourth step of analyzing the event diagram generated in the first step to order the received events; And a fifth step of extracting an event sequence for guaranteeing correct retry by determining a sequence of transmission events corresponding to the reception event determined in the fourth step. A computer-readable recording medium having recorded thereon a program capable of executing an event sequencing method of a distributed system that performs nondeterministic performance, A first step of generating an event diagram representing a relationship between events occurring in the execution of the distributed system by recording the performance of the distributed system using the monitoring server and the central monitor; A second step of analyzing the event diagram generated in the first step to order the non-deterministic received events; A third step of extracting an event sequence for guaranteeing correct retry by ordering transmission events corresponding to reception events ordered in the second step; And A computer-readable recording medium having recorded thereon a program capable of executing the fourth step of repeating the same retry while controlling to keep the transmission event sequence determined in the third step.