Quick Nav
- LimitChunkSize
- LimitClients
- LimitRequestBody
- LimitRequestFields
- LimitRequestFieldSize
- LimitResponseBody
- LimitUrl
- StartThreads
- ThreadLimit
- ThreadStackSize
See Also
Sandbox Directives
Appweb supports directives that limit its use of system resources such as memory and threads. This technique is know as "sandboxing" because it creates a limited / safer area in which Appweb executes.
LimitChunkSize
Description | Define the maximum chunk size |
Synopsis | LimitChunkSize size |
Context | Default Server |
Example | LimitChunkSize 8192 |
Notes |
This directive defines the maximum chunk size when using Transfer Chunk Encoding. |
LimitClients
Description | Set the maximum number of simultaneous clients |
Synopsis | LimitClient count |
Context | Default Server |
Example | LimitClient 10 |
Notes |
The LimitClient directive defines the maximum number of simultaneous client connections that are permitted. Client connection requests in excess of this count will be rejected. A limit of 0 means unlimited. NOTE that many browsers can and will initiate multiple connections when requesting a page. |
LimitRequestBody
Description | Set the maximum size of the request body from the client. |
Synopsis | LimitRequestBody limit |
Context | Default Server |
Example | LimitRequestBody 65536 |
Notes |
The LimitRequestBody directive defines a maximum size for the request body. For embedded applications, it is useful to limit the request body to the expected maximum. This ensures that rogue or malicious requests will not cause the server to allocate unwanted memory to servicing the request. The limit is an integer between zero and 2147483647 (2GB), where zero means unlimited. If a request is received that is larger than the limit, it will be rejected and the client will receive an error. The default limit is 64 MB. |
Security |
This directive can be quite useful in certain denial-of-service attacks where the attacker sends large documents of a certain type. |
LimitRequestFields
Description | Maximum number of header lines in the request body from the client. |
Synopsis | LimitRequestFields limit |
Context | Default Server |
Example | LimitRequestFields 64 |
Notes |
The LimitRequestFields directive defines a maximum number of header lines that may be in a request from a client. For embedded applications, it is useful to limit the number of header lines to the expected maximum. This ensures that rogue or malicious requests will not cause the server to allocate unwanted memory to servicing the request. Typically, HTTP requests will not have more than 15-20 header lines. The limit is an integer between zero and 4096, where zero means unlimited. If a request is received that has more header lines than the limit, it will be rejected and the client will receive an error. The default limit is 40. |
Security |
This directive can be quite useful in certain denial-of-service attacks where the attacker sends requests with many spurious header lines. |
LimitRequestFieldSize
Description | Maximum size of the request headers from the client |
Synopsis | LimitRequestFieldSize limit |
Context | Default Server |
Example | LimitRequestFieldSize 65536 |
Notes |
The LimitRequestFieldSize directive defines the maximum size of the request header from the client. For embedded applications, it is useful to limit the size of the header to the expected maximum. This ensures that rogue or malicious requests will not cause the server to allocate unwanted memory to servicing the request. Typically, HTTP requests will not have more than 4K of header data. The limit is an integer between zero and 1 MB, where zero means unlimited. If a request is received that has a header larger than the limit, it will be rejected and the client will receive an error. The default limit is 8 K. |
Security |
This directive can be quite useful in certain denial-of-service attacks where the attacker sends requests with large bogus headers. |
LimitResponseBody
Description | Set the maximum size of the response body buffered by a dynamic Appweb handler. |
Synopsis | LimitResponseBody number |
Context | Default Server |
Example | LimitResponseBody 65536 |
Notes |
The LimitResponseBody directive defines the maximum size for data generated by an Appweb handler that uses unchunked buffered output. Appweb handlers that generate dynamic output typically buffer output for performance. This directive places a limit on the amount of memory consumed by such buffering handlers. NOTE: this does not imply a maximum response size. It merely limits the memory consumed when trying to buffer the data. Appweb handlers will flush the buffer and use HTTP/1.1 chunked output if the amount of response data exceeds the output buffer size. The limit is an integer between zero and 4 MB, where zero means unlimited. These limits can be increased by recompiling Appweb using the source code. The default limit is 64K or 8K in squeeze mode. NOTE: this is a proprietary directive of Appweb and is not supported by Apache. |
LimitStageBuffer
Description | Defines the pipline stage buffer size |
Synopsis | LimitStageBuffer size |
Context | Default Server |
Example | LimitStageBuffer 8192 |
Notes |
This directive defines the maximum buffer size for each stage in the request pipeline. |
LimitUrl
Description | Maximum size of a URL in a request from a client. |
Synopsis | LimitUrl limit |
Context | Default Server |
Example | LimitUrl 4096 |
Notes |
The LimitUrl directive defines the maximum size of a URL in Appweb. IFor embedded applications, it is useful to limit the number of header lines to the expected maximum. This ensures that rogue or malicious requests will not cause the server to allocate unwanted memory to servicing the request. The limit is an integer between zero and 256 K where zero means unlimited. If a request is received that has a URL larger than the limit, it will be rejected and the client will receive an error. The default limit is 4 K. NOTE: this is a proprietary directive of Appweb and is not supported by Apache. |
Security |
This directive can be quite useful in certain denial-of-service attacks where the attacker sends requests with bogus URLs. |
StartThreads
Description | Number of threads to preallocate in the Appweb thread pool |
Synopsis | StartThreads number |
Context | Default Server |
Example | StartThreads 100 |
Notes |
The StartThreads directive will preallocate the specified number of threads on startup and then ensure that the thread pool always has at least this number of threads. Appweb will automatically adjust the number of pool thread between the minimum specified by this directive and the maximum specified by the ThreadLimit directive or via the Appweb command line. Appweb will prune idle threads to reduce resource consumption as required. |
ThreadLimit
Description | Maximum number of threads to allocate for the Appweb thread pool. |
Synopsis | ThreadLimit number |
Context | Default Server |
Example | ThreadLimit 8 |
Notes |
The ThreadLimit directive defines a maximum number of threads for the Appweb thread pool. When running in multithreaded mode, Appweb will use a pool thread to service each request and then will return the thread to the pool. This results in a highly responsive and scalable architecture with excellent throughput characteristics. Each thread requires a thread stack and thus consumes memory. By limiting the number of threads, memory can be conserved. If the maximum number of threads is also specified via the Appweb command line, the command line value will take precedence. Appweb will automatically adjust the number of pool thread between the minimum specified by the StartThreads directive and the maximum specified by this directive. Appweb will prune idle threads to reduce resource consumption as required. |
ThreadStackSize
Description | Define the size of the stack to allocate for each thread |
Synopsis | ThreadStackSize limit |
Context | Default Server |
Example | ThreadStackSize 65536 |
Notes |
The ThreadStackSize directive defines the size of the thread stack to allocate for each thread. The limit is an integer between zero and an operating system defined maximum where zero means use the system default. The default limit is 0 which implies the system default. If you are experiencing crashes when running multi-threaded and Appweb runs without error when running single-threaded, you may need to increase this value. See the Appweb command line for details on running single user by setting the "-p 0" option. |