Is there a limit to the number of concurrent requests Pholcus can handle?

Pholcus is a distributed, high concurrency and powerful web crawler software written in Go. It is designed to crawl and scrape web data at a large scale efficiently. However, like any software, the number of concurrent requests it can handle is influenced by several factors:

1. Hardware Resources: The CPU, memory, and network bandwidth of the machine on which Pholcus is running will limit the number of concurrent requests. More powerful hardware can handle more concurrency.

2. Network Conditions: The quality and speed of the network can affect how many concurrent requests can be made. A slower network may become a bottleneck.

3. Target Server Capacity: The web server being scraped can only handle a certain amount of load. If you exceed this, you may get throttled or blocked.

4. Software Configuration: Pholcus allows you to configure the concurrency level. This is usually set in the task configuration where you define the number of concurrent threads (goroutines in Go language terms).

5. Rate Limiting: You should also consider the ethical implications and legality of web scraping. Websites often have rate limits and terms of service that restrict how you can scrape their data.

In Pholcus, you typically define the concurrency level by setting the number of threads for the spider. Here is an example configuration in Go that sets up a Pholcus spider with a certain level of concurrency:

package main

import (
    "github.com/henrylee2cn/pholcus/exec"
    "github.com/henrylee2cn/pholcus/logs"
    _ "github.com/henrylee2cn/pholcus/spider_lib" // Import the spider library
)

func main() {
    // Set up the Pholcus runtime
    exec.DefaultRun("web") // "web" for web UI, "gui" for GUI, and "cmd" for command line

    // Configure the spider
    exec.SetThread(20) // Set the number of concurrent threads
    exec.SetPausetime(300, 1200) // Set pause time between requests

    // Start the crawler
    logs.Log.Informational("Starting Pholcus...")
    exec.Run()
}

In this example, exec.SetThread(20) sets the concurrency level to 20 threads. You should adjust this number based on your specific requirements and the factors listed above.

Keep in mind that if you set the concurrency too high without considering the target server's capacity and rate limits, you may end up being blocked or causing a denial of service on the server, which is both unethical and illegal.

Always scrape responsibly and consider using techniques such as rotating user agents, IP addresses, and adding delays between requests to minimize the risk of being blocked or banned by the target website.