Statistics guide¶
Zato’s service statistics allow one to observe trends in behaviour of services deployed on servers and to compare historical data in order to find weak spots and first symptoms of a misbehaving service.
They’re meant to be an aid for developers and administrators more than a strategical tool for making long-term decisions.
Another group of statistics are these produced by the load-balancer, concerning its current state - how many servers are up, whether there were any downtimes, how many clients are connected and more.
Service statistics¶
Each execution of any service prompts Zato to store certain statistics in the Redis broker:
- Which service has been invoked and when it was
- How long it took for the service to complete
- CID the service has been invoked with
Zato’s own internal (look up stats_jobs) scheduler’s jobs aggregate raw information into higher-order structures, all stored in Redis too - per minute stats are converted into per hour status, these get aggregated into per day information and so on until a summary information concerning each year has been constructed.
Note that the lowest level data that has been already aggregated is left in Redis and, unless it’s needed, must be cleaned up manually or using a custom job in order to avoid an unnecessary growth of Redis.
Trends and summaries¶
Trends are summaries are used to get an understanding of which services are the slowest ones and which ones are the most commonly used.
The difference between the two is that trends charts are generated on fly and they’re a heavy-weight operation. Trends should not be used for checking more than just a few hours worth of data.
Summaries are pre-computed, have no charts, and can span arbitrary datetime ranges, hours, days, months or even years.
Warning
Again, note that you shouldn’t use trends for displaying more than a few hours of statistics - doing so is a very intensive operation which effectively works as a DoS attack which needs restarting a server.
Understanding the interface¶
Both trends and summaries present a unified interface with the whole exception being that summaries have no charts
Statistics can always be downloaded in CSV
There are always at least two groups of statistics. If a side-by-side comparison has been chosen, there are also two groups of relevant statistics for the time period to compare with.
Each column in each group can be clicked to make the stats sorted by the column.
Hovering over a row highlights the same service in other groups.
All statistics always deal with the given time period selected only - for summaries this can be arbitrarily long.
Slowest services¶
| Column | Notes |
|---|---|
| Name | Service name |
| M | Service’s mean response time in milliseconds |
| AM | Average response of all services, including the service from the current row |
| U% | Service usage share as a percentage of all service invocations, i.e. CURRENT_SERVICE_USAGE / TOTAL_SERVICE_USAGE |
| T% | Service usage share as a percentage of time spent by Zato on processing all services, i.e. TIME_SPENT_BY_THIS_SERVICE / TOTAL_TIME_SPENT_BY_ZATO |
| TU | Total usage of all services |
| (Trend) | Shown for trends statistics only. A chart showing the trend of response times, the chart can be hovered over to get information on a concrete response in a given moment - the value is in milliseconds. 
|
Most commonly used¶
| Column | Notes |
|---|---|
| Name | Service name |
| U | How many times the given service was invoked |
| Rq/s | How many times a second the service was being invoked |
| U% | Service usage share as a percentage of all service invocations, i.e. CURRENT_SERVICE_USAGE / TOTAL_SERVICE_USAGE |
| T% | Service usage share as a percentage of time spent by Zato on processing all services, i.e. TIME_SPENT_BY_THIS_SERVICE / TOTAL_TIME_SPENT_BY_ZATO |
| TU | Total usage of all services |
| (Trend) | Shown for trends statistics only. A chart showing the trend of request rates, the chart can be hovered over to get information on many times a second the service was invoked in a given moment. 
|
Settings¶
scheduler -> How often to process raw statistics¶
How often to invoke a background job to turn raw statistics into per-minute statistics - default value lets some statistics be gathered in Redis before they’re aggregated.
The value should take into account how long it will take to process a single batch of statistics and how big the batch will be (next setting).
scheduler -> At most, how many raw statistics to process in one batch¶
When a background job starts to aggregate raw statistics, it will fetch at most that many raw data items from Redis.
This should be set in conjunction with the previous settings - proper values should take into account how many requests a second Zato processes.
For instance, if:
- How often to process raw statistics is 120
- How often to process raw statistics is 90000
- 90000 / 120 = 750 req/s
- This is the upper limit of raw data stored that Zato will make use of - if now the platform starts processing 900 req/s any additional requests will be ignored and the statistics will be incorrect.
The value should take into account how often the batches are fetched (previous setting) as processing of the previous batch should complete before a new one is started.
scheduler -> How often to aggregate per-minute statistics¶
How often to fetch per-minute statistics and turn them into statistics for each hour, day, month and so on. Should be no less than 60.
Attention grabbers -> Slow service threshold¶
If an average response time in less than this value, an attention grabber will be displayed to the left of the service name in trends.
Attention grabbers -> Top service usage threshold¶
If a given service’s usage share is more than this value, an attention grabber will be displayed to the left of the service name in summaries.
Last update:
Feb 24, 2014