Performance Testing Scenarios
Performance testing may be simplest if real-world scenarios are used that are drawn from the use patterns for Fedora 4. In other words, performance testing should be informed by the expected way Fedora will be used. No single software product can perform well for every possible use (a.k.a pattern of use). We need to define the expected uses for Fedora, and acknowledge the trade-offs that are being made. While we need to recognize that there will be unanticipated uses, we can only test for the cases that best characterize how we expect Fedora to be used. This sets expectations for those building systems using Fedora and guidance for Fedora committers. When there is a use is identified during system design, developers can decide if Fedora is suitable as a part of their implementation. Fedora committers can decide either Fedora can be extended to support that use or suggest how Fedora can be used in combination with other tools to support that use.
The scenarios are broken into major categories of use that give us examples of how Fedora is used to aid in constructing a realistic performance test suite. These are intended to be pragmatic categories since they present different loads on the system and should not be mechanically linked one-to-one with any API.
Definitions
- Use - Core action in a use case from the user's view
- User Operation - Users view of a logical, single operation
- Repository Operation - Repositories view of a logical, single operation
- Performance - The number of units of work that are accomplished during an operation
- Interleaving - The number and kinds of operations being performed at the same nominal time (as opposed to a single repetition of an operation)
- Unit of Work - A metric to be defined appropriate to the Fedora Repository.
- There may be more than one metric
- Working definitions:
- The amount in bytes of content and metadata for an operation, or per unit of time
- The number of operations per unit of time
- The time between when an operation is started and when it is completed
To Be Done
- Are these a good list of usage categories?
- Validate/Add user operations for each category (examples). Mark them as now, or future, or never? Note, if an external tool is needed. - This tell us how we expect Fedora 4 to be used.
- Add repository operations to each category?
- Map user operations to tests
- Choose performance units for each test
- Choose performance expectations for each test
- Construct interleaving matrix (to the limit of what is practical to accomplish) - Note: single thread tests will be use as a baseline as informed by Single Node tests
Usage Categories
The following categories and uses are drawn from the Fedora 4 Roadmap and any new items especially expectations that have surfaced during development. Only performance related uses are included, specific function details are dropped for simplicity and that they are likely not need specific performance testing.
Authoring
Authoring is the activity of creating or assembling new content. This includes both constructing wholly new content and referencing existing content. It is different from ingest in that is characterized by incremental assembly of the content which many rapid write/read cycles to accomplish what the user considers a single operation. It is often performed as part of some sort of authoring workflow commonly with multiple actors performing both overlapping and different roles. During this phase the content (and metadata) is rapidly changing. The time between operations in a workflow can vary considerably so Authoring needs to handle the shortest period between user operations.
User Operations
- In Islandora, I am using forms to create one or more items, and I am editing relationships incrementally
- In the National Science Digital Library (defunct), I have a constant stream of third party annotations being added
- In RepoMMan, I need the send a paper through an approval process where the approvers may want to make editorial changes
- In Hydra (I don't have one but I bet its there)
Repository Operations
- TBD - Map to API
Simple Ingest
Simple Ingest consist of upload of single or small amounts of content and metadata. It can be accomplished with a single atomic operation or a short series of operations, usually RESTful, without required intermediate reads prior to completion. The duration of the small ingest is expected to be approximately the time it takes to upload the content and metadata starting with the beginning of the connection, where the connection is terminated after the operation. It is expected that the ability to read (access) the uploaded content and metadata should happen fairly soon after the upload is complete.
User Operations
- I want upload an image through Hydra
- I want to upload a paper in NIST
- I am using a sync tools to upload a slow flow of new items
Repository Operations
- TBD - Map to API
Bulk Ingest
In bulk ingest, a large quantity of content and metadata is ingested as a logical unit or is continuous. This may be accomplished using number of repository operations or may utilize methods that are optimized for bulk ingest. It is characterized by the expectation that there may be a defined delay between when the ingest is started and part or all of the content and metadata becomes available for read.
User Operations
- I am the Bodleian Library and I want to create a duplicate (backup) of my digitised texts
- I am SIdora and I want to ingest the gene sequence for a Manakin (bird) coming from my in house gene sequencers
- I am using a sync tool to upload a new collection via I2
- I want to upload a 2000 graphs each consisting of 10000 items, and I want to be sure that each graph is complete, and the whole set is complete
Repository Operations
- TBD - Map to API
Simple Access
Simple access (a.k.a simple read or download) is the download of content and metadata (a.k.a representation of a resource) as a single user operation and one or a small number of repository operations. It usually RESTful, and usually contained a single request. Simple Access must not require any interleaved writes to accomplish the single user operation. The content and metadata stays fixed from the beginning to the end of the access.
User Operations
- I want to use the Exhibition module in Islandora to present a static website
- I want to present a dynamic website through Hydra
- I am using a sync tool to download a slow flow of new items
Repository Operations
- TBD - Map to API
Conditioned Access
When streaming media, dropouts present a significant problem. The user expects to be able to access the contents without interruption. This may require a front end tool for buffering so the stream need not be perfect but good enough for the buffering tool.
User Operations
- I am using Hydra to show a class lecture
Repository Operations
- TBD - Map to API
Mediated Access
Not all of the content is managed by Fedora but some resources are is provided by reference from a remote web service. Fedora would retrieve the representation (content and metadata) from the web service and present it as if it was a resource in Fedora.
User Operations
- I am using the Data Conservancy Service but I want so show Glacier images kept by the NSIDC
- I have papers stored in Islandora but I want to get the supporting datasets from SIdora
Repository Operations
- TBD - Map to API
Bulk Access
Download of large amount of content as single user operation. This may require any number of repository operations to accomplish. Whether content and metadata stays fixed from the beginning to the end of the operation is to be defined. This is needs consideration a whole intellectual entity, graph or DIP is considered the unit. Also we need to consider what this means for continuous access operations.
User Operations
- I am the Bodleian library and an EMP device went off. I need to use a sync tool to download a major set of digitized texts
- I am SIdora and I need to send a whole set of genome fragments to be assembled a ORNL
- I am Hydra and I need to send a SIP to APTrust and DPN
Repository Operations
- TBD - Map to API
Testing Matrix
Category | Uses | APIs | Test Metric | Test | Notes |
|---|---|---|---|---|---|
| Authoring | |||||
| Simple Ingest |
| Duration | |||
| Simple Ingest | Rate | ||||
| Bulk Ingest | Large Files - Mixed |
Testing Considerations
These scenarios expand on the previous single stimulus tests to use multiple read, write, and read-write tests via the REST api.
If the group think this is useful then I can break it into a matrix.
Note: all tests need to be taken until:
a steady state is achieved
a declining state is achieved
Fedora 4 no longer responds
Multiple Read
Stimulators
1 stimulator to provide a baseline similar to the previous testing regimen
3 stimulators
6 stimulators (since this is where Fedora 3 starts to exhibit limits)
12 stimulators (since this is where Fedora 3 always exhibits limits)
24 stimulators
Payloads
1K file
1M file
50M file (Avg Video)
2.7G file (DVD)
Rates
Step up rates X2 until flat line
Then proceed to declining response and failure or non-response
Multiple Write
Stimulators
1 stimulator to provide a baseline similar to the previous testing regimen
3 stimulators
6 stimulators (since this is where Fedora 3 starts to exhibit limits)
12 stimulators (since this is where Fedora 3 always exhibits limits)
24 stimulators
Payloads
1K file
1M file
50M file (Avg Video)
2.7G file (DVD)
Rates
Step up rates X2 until flat line
Then procede to declining response and failure or non-response
Read-Write
Stimulators
1 stimulator to provide a baseline similar to the previous testing regimen
3 stimulators
6 stimulators (since this is where Fedora 3 starts to exhibit limits)
12 stimulators (since this is where Fedora 3 always exhibits limits)
24 stimulators
Payloads
This needs to be matrixed. The payloads should be mixed but not randomly to make the tests repeatable.
1K file
1M file
50M file (Avg Video)
2.7G file (DVD)
Rates
Step up rates X2 until flat line
Then proceed to declining performance and failure or non-response
